





















H 







































































































THE ROMANCE OF 
MODERN PHOTOGRAPHY 










THE ROMANCE OF 
MODERN PHOTOGRAPHY 

ITS DISCOVERY & ITS ACHIEVEMENTS 


BY 

CHARLES R. GIBSON 

AUTHOR OF 

“the romance of modern electricity,” “electricity of to-day 

&c., &c. 


WITH SIXTY-THREE ILLUSTRATIONS 


PHILADELPHIA 

J. B. LIPPINCOTT COMPANY 

LONDON: SEELEY 6 s CO. Limited 
1908 


Tfr'is 

.Gt4- 


Printed in Great Britain 


/■/ i£ ,6 tfo 

'of 



PREFACE 


I T is not the author’s purpose in the present volume to 
give any instruction in the practice of photography. 
There are many useful works dealing with the prac¬ 
tical side of the subject. His object is to tell the romantic 
story of the discovery of this wonderful art, and the steps 
by which its range has been extended until it can achieve 
results which only a few years ago would have been 
thought impossible. A glance at the list of chapters 
will show what a wide field photography now covers, 
and what service it renders to man, both in his everyday 
life and in his most subtle scientific researches. 

The story has been told in the most readable form 
that the author could give it; but in an Appendix will 
be found a record of the successive incidents in the 
history of the invention, with the dates, and the names of 
the inventors, in a shape convenient for reference. 

The author is indebted to many friends for interesting 
information and references. Among these are Professor 
Korn, of Munich University; Professor Reiss, of Lau¬ 
sanne University; Professor Muir, of the West of Scot¬ 
land Technical College; J. Craig Annan, William Lang, 
Patrick Falconer, and John Trotter, of Glasgow. 

The author is indebted to the following gentlemen for 
very kindly reading the proof sheets of the chapters re- 


PREFACE 


lating to their special subjects: Dr. John G. McKendrick, 
f.r.s. (Emeritus Professor in the University of Glasgow), 
H. Stanley Allen, m.a., b.sc. (Senior Lecturer in Physics, 
King’s College, University of London), Dr. R. M. 
Buchanan (Bacteriologist to the City of Glasgow), Dr. 
J. Robertson Riddell (Royal Infirmary, Glasgow), W. B. 
Hislop (Lecturer on Process Work, Heriot Watt College, 
Edinburgh), and Inspector Stedman, New Scotland Yard 
(London). 

In connection with the illustrations the author is in¬ 
debted to Professor Korn, Professor Reiss, Edgar Senior 
(Battersea Polytechnic), Dr. W. J. S. Lockyer (Solar 
Physics Observatory), Dr. Vaughan Cornish, Arthur E. 
Smith, Richard Kerr, f.r.a.s., the Authorities at New 
Scotland Yard, London, the Criminal Investigation De¬ 
partment, Glasgow, and the West of Scotland Amateur 
Photographic Association. Also to the Librarian of 
Glasgow University, Dr. R. M. Buchanan, Charles 
Stewart, Alexander McGrouther, R. Brinkley and Sons, 
John Trotter, Glasgow; Rev. J. B. Thomson, Greenock ; 
and the Neue Photographische Gesellschaft, Berlin- 
Steglitz. The author is also indebted to the Thornton 
Pickard Company, Ltd., Altrincham, for the photographs 
of a pictorial character, and to J. A. Johnston and Com¬ 
pany, of 41 Snow Hill, E.C., for making the half-tone 
blocks for the illustrations facing pages 64, 82, 128, 180, 
210, 230, and 254. The author is indebted to Signor 
Ferdinand M. De Bianchi, Italian Consul at Madeira, for 
the photograph shown opposite page 268. 


8 


CONTENTS 


CHAPTER I page 

How Photography came to be Invented . . . 13 

CHAPTER II 

Early Photographs on Silvered Plates . 24 

CHAPTER III 

A Great English Inventor . . 44 

CHAPTER IV 

Instantaneous Photography . . 60 

CHAPTER V 

Can we Photograph in Colours? . . 72 

CHAPTER VI 

More about Colour Photography . . 93 

CHAPTER VII 

Colour Photography without Coloured Screens . . 107 

CHAPTER VIII 

The Making of Book Illustrations . . .116 

CHAPTER IX 

More about Book Illustrations . ... 127 

CHAPTER X 

The Three-Colour Process of Printing . . .142 

CHAPTER XI 

Photography and the Criminal . . . . 157 

9 


CONTENTS 


CHAPTER 

XII 



PAGE 

Photographing the Invisible 

• 

• 

• 

. 176 

CHAPTER 

XIII 




More Invisible Rays 

• 

• 

• 

. 196 

CHAPTER 

XIV 




Photographing Microbes, etc. 

• 

• 

• 

. 209 

CHAPTER 

XV 




Photographing under Difficulties 

• 

• 

• 

. 223 

CHAPTER 

XVI 




Telegraphing Photographs 

• 

• 

• 

. 234 

CHAPTER 

XVII 




Nature’s Camera 

• 

• 

• 

. 244 

CHAPTER : 

XVIII 




Some Interesting Achievements 

• 

• 

• 

. 260 

CHAPTER 

XIX 




Photographing the Stars . 

• 

• 

• 

. 275 

CHAPTER 

XX 




Photography and Science . 

• 

• 

• 

. 292 

CHAPTER 

XXI 




A Camera without a Lens, etc. 

• 

• 

• 

. 310 

CHAPTER 

XXII 




How Light makes the Photograph 

• 

• 

• 

. 320 

CHAPTER 

XXIII 




Conclusion 

• 

• 

• 

. 330 

Appendix 

. 



. 337 

Index . 


. 


. 343 


IO 


LIST OF ILLUSTRATIONS 

The Largest Photograph in the World (2 illustrations) Frontispiece 

FACING PAGE 

Exasperation and Retaliation (2 illustrations) . . . 16 

Daguerreotypes (2 illustrations) . . . . 30 

Fox Talbot’s Originals (2 illustrations) . 44 

Positive and Negative (2 Illustrations) . . 50 

Early Photograph of Criminals . . 58 

Wheel of Life . . . ... 64 

Cinematograph Film . . ... 70 

Two Instantaneous Photographs (2 illustrations) . . 82 

A Bad Fall . . . ... 94 

Ten Photographs of Five Criminals . . . . 108 

Three Criminals and their Thumb Marks . . .118 

Photograph taken through a Coarse Screen . .128 

A Print by the Three-Colour Process (4 illustrations) . 146 

Simple Demonstration of Three-Colour Printing (5 illust.) 154 
Finger-Prints Marked for Jury . . . . 160 

Cash Box and Finger-Prints . . . . 172 

X-Ray of Lady’s Arm . . . . . 180 

Portrait taken without Visible Light, etc. (2 illustrations) 196 
Invisible Bloodstains on Handkerchief, etc. (2 illustrations) 206 
Spider’s Foot . . . ... 210 

Microscopic Shells (2 illustrations) . ... 216 

Well-known Bacteria (4 illustrations) . ... 220 

Down in a Coal-Mine (2 illustrations) . ... 230 


11 





LIST OF ILLUSTRATIONS 

FACING PAGE 

Telegraphed Photographs (2 illustrations) . . . 240 

Model of Human Eye (2 illustrations) . ... 248 

Demonstration of Bending Light (2 illustrations) . . 254 

Stereoscopic Photographs . . ... 258 

Portuguese Diving . . . ... 268 

Telephotograph of St. Alban’s Abbey (2 illustrations) . . 284 

Crossing Waves ; Current Mark on Sand (2 illustrations) . 298 

Cloud Formation; Dark Lightning (2 illustrations) . . 308 
Pinhole Pictures (2 illustrations) . . . . 316 

Canterbury Cathedral (interior) . • . . 328 

Process Screen (in text) . . . . . 132 

Earthquake Record (in text) . . . • • 3°5 


12 


THE ROMANCE OE 
MODERN PHOTOGRAPHY 


CHAPTER I 

HOW PHOTOGRAPHY CAME TO 
BE INVENTED 

An amusing incident—Early invention of the camera obscura—Photo¬ 
graphy foreshadowed in early fiction—An interesting legend about 
one of the alchemists—Some early experiments in London. 

T HERE are few readers who require to have the 
general principles of photography explained to 
them. Almost every one is quite familiar with the 
dark camera, the exposure of the sensitised plate, the 
later developing and fixing of the image by chemical 
processes thereby producing a negative, and finally the 
paper picture obtained by contact printing by daylight. 
The general public were not always so well versed in 
photographic methods. I can well remember, some 
twenty years ago, when, in country districts, one found 
people surprised that the photographic artist “could 
draw that quickly”; the idea being that he drew the 
pictures by hand the while he disappeared beneath his 
focussing cloth. 


i3 


HOW PHOTOGRAPHY 


One sometimes found well-educated townspeople fail¬ 
ing to grasp the first principles of photography. I 
remember one incident when an early enthusiast was 
staying in the country. He wrote asking a friend, who 
was about to pay him a visit, to bring with him some 
photographic plates. The friend when he arrived ex¬ 
plained that these photographic plates had given him 
a fright. He had let them fall by accident, and, fearing 
they might be broken, he had opened the box on the 
journey, and was quite relieved to find that there was not 
even a crack on any of the plates. We can imagine his 
feelings when he was informed that the plates having 
been once exposed to light were absolutely useless. 

We have become so accustomed to photography that 
it will be of interest to see how man discovered this art. 
We hardly expect to find that photography was invented 
by a certain man on a certain date, and yet there must 
have been a first photograph. Our difficulty is to know 
which of the early attempts we can really call a photo¬ 
graph. There are, however, a few names which stand 
out very prominently in connection with the invention of 
photography. All invention is more or less an evolution ; 
a simple association of ideas. The ideas and discoveries 
of one generation lead on to the further discoveries of 
the succeeding generation. In some cases progress is 
very slow, while in others vast strides are rapidly made. 
Previous to the dawn of the nineteenth century all 
scientific progress was necessarily slow, for information 
travelled very slowly. Man had to carry intelligence 
from one place to another. News could not then be 
flashed to the ends of the earth with lightning speed, 

14 


CAME TO BE INVENTED 


nor did there exist any steamers to race across the oceans. 
Just as in the case of electricity we find an important 
discovery lying dormant for many centuries, so we find 
the basis of photography discovered hundreds of years 
before there was any practical application. To those who 
have not already considered the matter it may at first 
seem somewhat strange that the camera should have 
existed for nearly three hundred years before photography 
was invented. 

In the middle of the sixteenth century there lived an 
Italian philosopher, Battista Porta, who exhibited what 
we know as a camera obscwra . All he did was to put a 
tightly fitting shutter on his window, so that no light 
could enter, except by a small hole which he had cut in 
the centre of the shutter. This hole was in size rather 
less than would permit the little finger to pass through. 
When this was done there appeared upon the opposite 
wall of the room an inverted image of the outdoor scene 
immediately in front of his window. Indeed, there was a 
facsimile of the view he had from his window, except that 
everything was standing on its head. The philosopher 
went into raptures, crowds flocked to his house in Naples 
to see these “pictures painted by light, glowing with 
colour and marvellously accurate.” It has been stated 
by many that Battista Porta invented the camera obscura , 
but there are records of such cameras prior to Porta’s 
time. Many of us have probably seen the same phenomenon 
accidentally produced at one time or another. I can well 
remember, as clearly as though it were but yesterday, 
when, at the age of ten, I came downstairs early one 
bright summer morning before the outer front door had 
i5 


HOW PHOTOGRAPHY 


been opened, I was very much surprised to see on the 
ground glass of the inner door an inverted image of 
the fields and trees in front of the house, every detail 
being most faithfully reproduced. I can remember 
that I was not satisfied till I learned the cause of the 
picture being upside down. No doubt the reason for this 
is patent to most readers, but if not the matter will be 
made clear when we come to consider “ Nature’s Camera.” 

Battista Porta caused the image to fall upon a white 
surface so that the details might be more clearly seen ; an 
experiment which may be very easily repeated by any one. 
About this time it was also found that the image could 
be improved by placing a glass lens at the hole in the 
dark shutter. This gave a much brighter and what photo¬ 
graphers call a sharper picture. The lens was not a 
new invention. People were well acquainted with glass 
lenses; they were in common use long before this time, 
having been worn in spectacles for some two hundred and 
fifty years before this. The idea of glass lenses, where¬ 
with to focus light, must have been of very early origin, 
for there may be seen in the Assyrian department of the 
British Museum a glass lens which was found in the ruins 
V of Nineveh (1000 b.c.), that great city on the top of 
whose high walls three chariots could drive abreast around 
its sixty-mile circumference. There is, of course, the 
possibility that this ancient lens was merely used as an 
ornament. 

The introduction of the lens into the camera obscura 
still left the image upside down. A mirror placed close 
to the lens caused the light to be thrown down through 
the lens on to a horizontal table instead of its falling 
16 



By -iermissiofi of M'Caiv, Stevenson, and Orr, Ltd, 

Exasperation and Retaliation 

These photographs make a story without words. These were taken by Miss Agnes 
Tomlinson in one twenty-fifth part of a second by means of a Thornton-Pickard Im¬ 
perial Camera and studio shutter. 




















» 










































































CAME TO BE INVENTED 


upon the upright wall. The observer could then view 
the picture in its natural position by merely taking his 
stand at the base of it without the necessity of standing 
on his head. 

When it became known that the necessary apparatus 
was so very simple, these dark chambers or camera ob- 
scuras became a source of amusement in the country 
houses of the wealthy. We still find a few such instru¬ 
ments exhibited in large cities by way of entertainment. 
I remember how, many years ago, one of my mother’s 
maids returned from a visit to the Scottish capital, filled 
with delight and wonderment at what she had seen at the 
“dispensary.” It seemed strange that the girl should 
have included a dispensary in her sight-seeing, but on 
cross-examination it was found to be a camera obscura. 
Possibly her idea was that the light dispensed the picture 
upon the table. 

The idea of trying to catch and fix these pictures of 
Nature may have occurred to many, but to the majority 
of 'people it would seem an absolute impossibility. Some 
early writers of fiction described Nature herself producing 
pictures; very possibly the idea was suggested by these 
sixteenth-century camera obscuras. Late in the seven¬ 
teenth century one writer imagines himself transported to 
a far country where pictures were produced in the following 
manner. Great vessels made of gold and silver were filled 
with water. The surface of the water reflected the sur¬ 
rounding scene, but, strange to say, the water then froze 
and retained the picture permanently. About the middle 
of the eighteenth century another writer of fiction dreams 
he is in the very heart of Africa, where he is conducted 
17 


B 


HOW PHOTOGRAPHY 


by his guide into a darkened chamber. He saw out of 
a window a great sea which seemed to be a quarter of a 
mile distant. We can imagine his surprise upon seeing 
the ocean in the centre of Africa. It seemed to him a 
miracle, as his own words will show. 64 1 hastily ran to 
convince my eyes of so improbable a thing. But in trying 
to put my head out of the window I knocked it against 
something that felt like a wall. Stunned with the blow, 
and still more with so many mysteries, I drew back a 
few paces. 

444 Thy hurry,’ said the guide, 4 occasions thy mistake. 
That window, that vast horizon, those black clouds, that 
raging sea, are all but a picture. The elementary spirits 
have composed a most subtle matter, by the help of which 
a picture is made in the twinkle of an eye. They do over 
with this matter a piece of canvas, and hold it before the 
objects they have a mind to paint. The first effect of the 
canvas is that of a mirror. But what the glass cannot do, 
the canvas, by means of the viscous matter, retains the 
image. The impression of the images is made the first 
instant they are received on the canvas, which is im¬ 
mediately carried away into some dark place. An hour 
after, the subtle matter dries, and you have a picture so 
much the more valuable as it cannot be imitated by art 
or destroyed by time.’” So runs the tale, which was 
written by Tiphaigne de la Roche, in 1760, under the 
title of Giphantie. This was assuredly a fanciful dream, 
and yet it is a fair description or prediction of what we 
have now accomplished. 

How many people may have made serious attempts to 
fix the image of the camera obscura is not known. At 
18 


CAME TO BE INVENTED 


least three experimenters were successful, and of these two 
were natives of France, while the third was the grandson 
of an English earl. 

What is the earliest date at which photography became 
possible ? One might say that it would have been quite 
possible for Battista Porta to have in some measure fixed 
his Nature’s drawings, as the necessary chemicals were 
known then to the alchemists. There is a legend that, 
just about the same time that this famous Italian philoso¬ 
pher was exhibiting his camera obscura , one of these 
alchemists, who was seeking in vain for the philosopher's 
stone or the elixir vita?, chanced to drop some ordinary 
sea-salt into a solution of silver nitrate, whereupon the 
liquid became white like milk. This phenomenon by 
itself would not astonish the alchemist, but he observed 
that when sunlight fell upon this white liquid it very 
quickly turned black. However, as this new phenomenon 
did not seem to lead towards either of the goals for which 
the alchemist was striving, he did not reckon it of much 
importance. These old-time alchemists were by no means 
all rogues or charlatans; many of them earnestly sought 
after the philosopher's stone and the elixir vita?. They 
really believed that they might succeed in transmuting the 
baser metals into precious gold and silver, and that they 
might also discover some panacea which would prolong life 
indefinitely. With the recent discoveries of radium and 
radio-activity, who can say that man may not some day 
see such transmutations of metals ? We now see the 
immutable atom of a few years ago breaking up into 
other forms of matter; it is true this newly discovered 
action of Nature is only a transmutation on a very small 

19 


HOW PHOTOGRAPHY 


scale, but scientists are not going to be dogmatic and say 
that it will for ever be impossible to hasten this process. 
Many scientists of a century ago even believed photo¬ 
graphy to be for ever an impossible thing. 

I imagine that as regards the second goal of the 
alchemist—the indefinite prolongation of life—the most 
of us are ready to be dogmatic, despite the ingenious sug¬ 
gestions of Professor MetchnikofF, of the Pasteur Institute. 
This learned gentleman believes that were it permissible 
to prepare certain serums and inject them into the human 
body old age would be defied. However, to return to the 
alchemists, we find that they treated the study of chemi¬ 
cal phenomena in very much the same spirit as the 
astrologers looked upon a knowledge of the stars. To the 
astrologer the only useful purpose in a study of the heavenly 
bodies was to enable him to foretell future events and per¬ 
chance in some mysterious way to influence them. So it 
was with the alchemist; he treated his discoveries lightly 
if they did not seem to take him nearer his twofold goal. 
Nevertheless these men made many discoveries which are 
of much importance to us to-day. 

Despite the existence of the legend to which I have 
referred, it seems doubtful whether or not the alchemists 
were really aware of the action of light upon silver salts, 
although it is certain that these men made silver nitrate. 
In any case, it was well known in the sixteenth century 
that silver ore sometimes changed colour when brought 
up from the mines. If the alchemists did know of this 
property of silver salts, it is clear that they did not consider 
the phenomenon of much importance; it is certain that 
the subject did not attract any attention. It is interesting 


20 


CAME TO BE INVENTED 


to note that a German physician, some two centuries 
later, amused his friends by making up a mixture of chalk 
and silver nitrate in a bottle, and then exposing the bottle 
to sunlight. He cut out designs and words in card¬ 
board, after the manner of stencils, and when he allowed 
sunlight to shine through these upon the contents of his 
bottle, there appeared the same design or word in black 
upon the chemical mixture. Shaking the bottle well 
caused the image to disappear, whereupon the bottle was 
ready for another performance. It has been suggested 
that this man should be called the inventor of photo r 
graphy—but he really only invented a conjuring trick. 
Leaving the alchemists out of account, this man may 
have been the first to note the darkening effect of light. 

Early in the nineteenth century Wedgwood, a son of 
the famous English potter, made some interesting experi¬ 
ments with silver salts. Wedgwood was assisted in some 
of these experiments by the great Sir Humphry Davy, 
who did so much pioneer work for chemistry and elec¬ 
tricity. These two experimenters coated paper, and also 
white leather, with a weak solution of silver salts. They 
then laid opaque objects upon the prepared surface, and 
thus caused the shadows of the objects to imprint them¬ 
selves. In other words, the paper turned black on ex¬ 
posure to light, except at those places where the paper 
was protected from the light by the intervening objects. 
The result was a white print upon a black ground. 

These experimenters tried some of their prepared paper 
in a camera obscura , but without any result. Their 
failure was no doubt due to the want of intensity in the 
light which passed into the camera obscura , for Davy 


21 


HOW PHOTOGRAPHY 


afterwards succeeded in producing images of objects 
placed in a solar microscope 1 which had a more concen¬ 
trated light. With a modem camera and ordinary 
photographic paper it is quite easy to take a photograph 
directly on to the paper in the camera, provided a 
sufficiently long exposure is given. 

Wedgwood and Davy succeeded in copying paintings 
on glass by placing them in contact with a sensitised 
paper, but they do not seem to have considered the sub¬ 
ject to be of much practical importance. They were not 
able to fix the image permanently; the light soon black¬ 
ened the whole paper and therefore destroyed the picture. 
One may be a little surprised that our illustrious chemist, 
Humphry Davy, did not devise some means of fixing the 
paper print, and the surprise is increased when one learns 
that all that was really necessary was to dip the print in 
salt water. Wedgwood and Davy did make some at¬ 
tempts to fix the picture by washing the prints thoroughly 
and by coating the surface with varnish, but these 
methods failed to prevent the further action of light. 
Referring to the possibility of fixing such prints, Davy 
wrote: “ Only this is wanting to render the process as use¬ 
ful as it is elegant.” I have said that one may be sur¬ 
prised to learn that Davy failed in overcoming so simple 
an obstruction, but I cannot think that he really gave 
the matter any very earnest attention, for he was at this 
time deep in chemical and electro-chemical research work, 
which, no doubt, appealed to him as being of far greater 
importance. It may be remarked in passing that these 
experiments made by Wedgwood and Davy had also been 

1 The solar microscope was practically a sunlight magic lantern. 


22 


CAME TO BE INVENTED 


made abroad more than half a century previously, but 
these two English experimenters do not appear to have 
been aware of this fact . 1 

This is how matters stood at the beginning of the nine¬ 
teenth century, and indeed at the time when our late 
Queen Victoria was a girl. Then followed three separate 
romances, the discoveries of Niepce, Daguerre, and Talbot, 
the three pioneers already referred to, the first two being 
French and the third an Englishman. 

1 Names and dates not detailed in this chapter will be found in the 
Appendix at page 337. 


23 


CHAPTER II 


EARLY PHOTOGRAPHS ON 
SILVERED PLATES 


Large prices paid for early photographs—The reason why—A famous 
scene painter—“Is Daguerre mad?”—Daguerre finds he has a 
rival in Niepce—Strange story of another unknown rival—How 
Niepce made his pictures—Daguerre and Niepce enter into partner¬ 
ship—An accidental discovery makes photography a practical 
success—How daguerreotypes were made—Daguerre fails to float 
a company—A great speech in the French Chamber of Deputies— 
Government pensions for the inventors—Have the historians mis¬ 
represented Daguerre’s character ? 

M ANY of us have in our possession small leather 
cases or frames containing pictures of our grand¬ 
parents. These pictures are on metal and are 
usually protected by a glass cover. These are the earliest 
productions of photography, and are known as daguerreo¬ 
types, having been so called after the inventor of the 
process. There are doubtless some elderly people now 
living who can remember the opening of the first studios 
for the production of these pictures in 1840. 

Our grandfathers did not have their photographs taken 
so often as we do; it was in their time a very expensive 
luxury. Our own calls upon the photographer would be 
less frequent if we had to pay from two and a half to 
four guineas for one single copy, and yet these were the 
actual prices paid during the first fourteen years. Why 
24 


EARLY PHOTOGRAPHS 


such exorbitant prices? In the first place the photo¬ 
grapher could not accept an order for a dozen copies; he 
could only give the one copy which he took in the camera. 
Then again the picture was produced on a polished silver 
surface and considerable skill was required, especially in the 
preparation of the plate, so that the prices were really not 
so exorbitant. The case was very different from that of 
the photographer of the present day, who may receive 
orders for several dozen photographs all produced at small 
expense from one single negative. 

Those who possess daguerreotypes should preserve them, 
as they are becoming rare. In the accompanying illustra¬ 
tions (facing p. 30), we have photographs of two of these 
early daguerreotypes, taken nearly sixty years ago. The 
daguerreotype in the left-hand illustration is in the 
possession of the West of Scotland Photographic Society, 
who kindly gave me permission to copy it. The right- 
hand illustration is from a photograph of a daguerreo¬ 
type, the original of which cannot be found by a friend who 
has very kindly been searching for it. This daguerreotype 
is of historic interest, as it not only shows the late Queen 
Victoria and the Prince Consort, but also Napoleon III 
and his wife. It was taken in 1854, when the 1851 Ex¬ 
hibition buildings were reopened as the Crystal Palace. 

It will be of interest to follow Daguerre’s career so 
far as that relates to the invention of this process of 
photography which bears his name. Early in the nine¬ 
teenth century Daguerre distinguished himself as a scene 
painter for the theatres in Paris. He had been some¬ 
what neglected by his parents and allowed to drift into 
any occupation that attracted him. Daguerre was an 

25 


EARLY PHOTOGRAPHS 


enthusiast, and in addition to exhibiting originality as an 
artist, he introduced many ingenious stage effects. Along 
with another artist he painted a diorama, which was a kind 
of panorama with what we should now call u dissolving 
views” in connection with magic lanterns. This was 
shown in Paris in 1822 and brought Daguerre much fame. 
He, and many other artists, made use of the camera 
obscura when making sketches from Nature. Our old 
friend Battista Porta made this suggestion at the very 
outset. Sometimes the artist would carry a small dark 
tent with him, wherein he would sit and make sketches 
from the picture “ drawn by Nature ” upon the white 
screen before him. Daguerre became possessed of a great 
desire to fix those pictures without requiring to copy them. 
He became so enthusiastic about this that he is said to 
have spent nine-tenths of his whole time in his laboratory. 
As time went on, his wife became alarmed. Was her 
husband going mad ? Was he striving after something 
which was perfectly ridiculous ? She consulted one of the 
well-known men of science, but the most comforting 
assurance she could get was to this effect: “ In our present 
state of knowledge it is impossible, but it may not always 
remain an absolute impossibility.” 

Daguerre’s first attempts were with paper soaked in 
silver salts; just such experiments as had been tried by 
Wedgwood and Davy, as related in the preceding 
chapter. Despite all his patient toiling, Daguerre seems 
to have met with little success in this direction, although 
we have already seen that the thing is possible, provided 
sufficient light enters the camera. 

It so happened that the optician in Paris from whom 
26 


ON SILVERED PLATES 


Daguerre bought his apparatus, and who was aware of 
Daguerre’s experiments, chanced to have, as a customer, 
another scientific enthusiast, who was earnestly seeking 
after the same goal. This other would-be inventor was 
Joseph Nicephore Niepce, who lived far away from Paris, 
at Chalons-sur-Saone. Niepce 1 was of a much more reticent 
nature than Daguerre, and, living at a distance, his calls 
at the optician’s shop were much less frequent than those 
of Daguerre, who called regularly once a week. The 
Paris optician, Charles Chevalier, informed Daguerre that 
another gentleman was also making experiments, with the 
hope of fixing the image of the camera obscura. Daguerre 
thereupon wrote to Niepce informing him that he too was 
busily engaged upon this subject, but Daguerre received 
no reply to his letter. Niepce put the letter in the fire, 
believing it was merely a ruse on the part of some one 
anxious to obtain his secret. In about twelve months 
Daguerre tried again to get in touch with Niepce, stating 
that he had arrived at important though imperfect results. 
Daguerre suggested that it might be advantageous to 
both if they were to make a mutual exchange of their 
secrets. Niepce made inquiries regarding Daguerre, and 
evidently was satisfied that his claims were genuine, for 
a correspondence was begun between these two inventors, 
who, later on, exchanged samples of their work, and 
ultimately met, and signed a co-partnery agreement. 
Each partner agreed to make known to the other his 
present and future achievements. 

In the preceding chapter I remarked that the idea of 

1 There seems to be some question about the proper pronunciation 
of this word, but the best authorities pronounce it Nee-ejps . 

27 


EARLY PHOTOGRAPHS 


trying to fix the image of the camera obscura may have 
occurred to many people. There was at least one other 
man working at this problem in secret, and he evidently 
met with considerable success. His existence might never 
have been made known to us, but for a chance call which 
he made at Chevalier’s shop. Chevalier tells us that one 
day a very shabbily dressed young man entered his shop 
and inquired the price of a certain camera. The man 
was pale and miserable-looking, and altogether very 
unlike the probable purchaser of a camera. When 
Chevalier told him the price the young man looked very 
disappointed, and stood dumb. The optician asked him 
if he might inquire to what purpose the young man pro¬ 
posed putting the camera. The youth hesitated a moment 
and then said that he had succeeded in fixing the image of 
the camera on paper, but that he had only a very rough 
piece of apparatus to work with. He declared, however, 
that he had already obtained such good pictures from his 
window that if he could only get a good camera his 
invention would be perfect. Chevalier thought to himself 
—another poor fool striving after the impossible. Possibly 
he gave outward signs of his disbelief, for the young man 
produced from an inside pocket a very tattered-looking 
pocket-book. We can imagine Chevalier’s surprise when 
the young man laid upon the counter a view of Paris. 
Chevalier could not control his astonishment—it was quite 
clear that this picture was not the work of the hand of 
man; it could not be mistaken for a drawing, nor for 
a painting in black and white. 

This struggling inventor seems to have been very frank 
about his methods, for he handed Chevalier a bottle of 
28 


ON SILVERED PLATES 


a blackish fluid, with which he said he had obtained the 
picture. The young man promised to return, but never 
appeared again, and we can only guess that his fate was 
a sad one. It is even possible that he may have died of 
want, or dragged out his remaining days in some obscure 
alms-house. One feels inclined to speculate as to what 
might have been, had Chevalier only thought of lending 
the poor fellow the necessary apparatus, and giving him 
some assistance until his invention was perfected. We 
might then have had this unknown man’s name handed 
down as the inventor of photography, for this event 
occurred in 1825, at which date neither Niepce nor Daguerre 
had produced such pictures. However, it is very prob¬ 
able that Chevalier did not mean to lose sight of this 
remarkable youth. No doubt Chevalier was so much sur¬ 
prised at the whole meeting that it did not occur to him 
even to ask the stranger’s name and address. 

Chevalier tells us that he tried to fix the image of the 
camera by means of the solution which the stranger left 
with him, but without success. It is most likely he did 
not know how to handle the solution ; indeed, it is possible 
that he may have exposed the liquid to light and thus 
rendered it useless before he ever tried to make use of it. 

Chevalier informed Daguerre of this stranger’s visit, 
and he gave the remainder of the solution to Daguerre, 
who also failed to get any result. The fact that Chevalier 
actually saw the “ photograph ” himself is, however, proof 
of the genuineness of the young man’s claims. 

To return to Niepce, who was more fortunate in pos¬ 
sessing an ample supply of this world’s goods; we find 
that Niepce had been at work upon this problem for ten 
29 


EARLY PHOTOGRAPHS 


years before he met Daguerre. It was generally known at 
this time, at least among chemists, that many substances 
were affected by light. The tanning which our faces get 
in summer at the seaside might suggest to the least ob¬ 
servant that sunlight produced some chemical effect upon 
the skin, even were he ignorant of the cause of the negro’s 
colour. 

There was a mineral substance, doubtless of vegetable 
origin, which is known as bitumen of Judea; a sort of 
asphalt or pitch, and sometimes called “Jew’s pitch.” 
This material when dissolved with some oils was affected 
by exposure to light, but an exposure lasting many hours 
—and in sunshine—was necessary. It is not quite clear 
whether Niepce discovered this property of bitumen, or 
whether it had been previously observed. Niepce spread 
his preparation of bitumen upon a tablet of plated silver 
or well-cleaned glass. There were many careful operations 
required, and some knowledge of the great care which was 
necessary may be gleaned from one sentence in Niepce’s 
description of his process. In explaining that the pre¬ 
pared plate must be protected from a damp atmosphere, 
he says: “ In this part of the operation a light disc of 
metal, with a handle in the centre, should be held before 
the mouth, in order to condense the moisture of the 
breath.” 

At first Niepce contented himself with making contact 
prints on these prepared tablets, just as Wedgwood and 
Davy had done on paper soaked in silver salts. After 
meeting with success in reproducing engravings, etc., the 
paper being made translucent by oiling or waxing it, 
Niepce endeavoured to secure the image of the camera 
30 


-• -i 



The photographs, from which the above have been reproduced, were taken on silvered-copper plates, at 
the opening of the Great Exhibition of 1851 (London). The right-hand photograph is of particular interest. 
The four figures in the front are Napoleon III., Queen Victoria, the Empress Eugenie, and the Prince 
Consort. (See chap, ii.) 





































































































































































ON SILVERED PLATES 


obscura. The action of the light was such that those 
parts of the preparation exposed to it were so altered in 
chemical condition that they became insoluble in the oils 
by means of which the bitumen had been previously dis¬ 
solved. This was very convenient; it allowed Niepce to 
dissolve away all the bitumen except those parts which 
had been affected by light. The result was that the 
remaining parts of the film produced only a silhouette, or 
black profile of the picture of the camera obscura. For 
his earliest experiments Niepce used a camera made out 
of a cigar box, with a lens taken from an old solar micro¬ 
scope belonging to his grandfather. One great cause of 
defect in those pictures must have been the very long 
exposure necessary. This extended sometimes to six or 
eight hours, and during that time the shadows on the 
scene being photographed would have moved practically 
right across the plate. 

When the partnership was entered into between Niepce 
and Daguerre, the former seems to have been able to 
produce the best results. Daguerre soon made many 
improvements in Niepce’s process, and he evidently aban¬ 
doned his previous experiments with silver salts altogether. 
However, Daguerre soon became dissatisfied with the long 
exposure necessary, and he earnestly sought after some 
quicker process. 

It may be remarked in passing that Niepce did not call 
his process photography but heliography, or sun drawing. 
Niepce died in 1833, before any commercial success had 
been attained, and the process which did meet with suc¬ 
cess was quite different from that at which Niepce had 
been working. It is said by many writers that Niepce’s 
3i 


EARLY PHOTOGRAPHS 


son who followed him in the partnership was quite willing 
that the successful process should be called “ daguerreo¬ 
type, 1 ’ thus taking no notice of the Niepce-Daguerre 
agreement. I think there must have been some error on 
the part of these historians, for there was a book pub¬ 
lished in Paris, in 1844, by Niepce’s son, which seems to 
contradict this statement. Its title translated into 
English reads, “History of the discovery improperly 
called 4 daguerreotype,’ preceded by a notice of the real 
inventor, the late M. Joseph Nicephore Niepce, by his 
son, Isidor Niepce.” In the light of this publication the 
general statement that Niepce’s son agreed to the title 
seems quite untenable. 

Before his meeting with Daguerre, Niepce senior had 
visited his own brother in London. He had taken with 
him some of his pictures, presumably photographic copies 
of engravings. It was suggested that he should read a 
paper, relating to his heliography, before the Royal 
Society, but as he was not willing to divulge the parti¬ 
culars of his process the Society could not accept the 
paper. Niepce did not consider his process by any means 
perfect, and he was therefore unwilling to publish an 
account of it. Niepce only lived a few years after he 
entered into partnership with Daguerre, and it was not 
till about five years after the death of Niepce that 
Daguerre made the discovery which made photography 
practicable. 

How then did this discovery come about ? It hap¬ 
pened in a most interesting manner. Our interest is 
always stirred by any discovery made by accident. It is 
certain that the first man who observed that silver salts 


32 


ON SILVERED PLATES 


were blackened by exposure to sunlight must have made 
the discovery by accident. He was not seeking to discover 
a substance which would be blackened by sunlight. The 
discovery of the principle of the camera obscura in the 
middle ages, no doubt, could be classed as accidental, but 
not so the experiments of Wedgwood and Davy, nor those 
of Niepce. These experiments therefore appear more 
commonplace. As children our interest was stirred by 
such stories as that of Archimedes, the ancient mathe¬ 
matician (287 b.c.). We could sympathise with him in 
his difficulty of how to find what quantity of alloy had 
been fraudulently mixed with the gold in the “pure 
gold” crown ordered by King Heiro. And when Archi¬ 
medes visited the baths, still thinking of his problem, 
and observing that his body displaced a certain amount 
of water, which he reasoned must equal the weight of his 
body, we could enter into his excitement as he rushed 
home, undressed, shouting, “Eureka! Eureka!” (“I have 
found it! I have found it! ”). Daguerre’s excitement 
similarly knew no bounds when he first imperfectly fixed 
the image of the camera obscura. He exclaimed, “ I have 
seized the light! I have arrested his flight! The sun 
himself in future shall draw my pictures ! ” 

Daguerre had abandoned the bitumen process of his 
late partner Niepce, as also his own early experiments 
with silver salts, but he was evidently seeking once more 
to engage silver, in some form or another, in his service. 
It is said that Daguerre accidentally discovered that a 
plate treated with iodine was sensitive to light. We are 
told that on one occasion he noticed that a plate which 
had been treated with iodine retained the image of a 


c 


33 


EARLY PHOTOGRAPHS 


silver spoon which had chanced to be laid down upon it. 
Although I can only find one historian who has preserved 
this tale for us, it seems a very probable one. Daguerre 
had already seen Niepce use iodine to blacken his bitumen 
pictures, so that iodine would be sure to be among 
Daguerre’s stock of chemicals. It would be quite natural 
that he should try to improve his own pictures by expos¬ 
ing them to the vapour of iodine, just as Niepce had done, 
and no doubt it would be upon a plate which he had thus 
treated that he accidentally discovered the image of a 
spoon. This would suggest to him at once that iodine 
would make his silver plate sensitive to light. 

This iodine, with which Daguerre was working, had not 
been long discovered. It is an elementary substance, and 
was obtained by some chemical manufacturers from sea¬ 
weed. Daguerre took a brightly polished plate of silver 
and sought to make its surface sensitive to light by ex¬ 
posing it to the vapour of iodine. Alas, when Daguerre 
exposed his plate in the camera, he could only get a very 
faint sort of image of bright objects, and that after many 
hours of exposure. It seemed as though the hopes which 
he had built upon his silver plate, with its coating of 
iodide of silver, was going to share the same fate as his 
earlier experiments with paper soaked in silver salts ; in¬ 
deed, matters looked even more hopeless. It so happened 
that one day he removed one of these silver plates from 
his camera, as the exposure—probably due to poor light— 
had been insufficient to produce any image. Had the 
spoilt plate been a glass one or a prepared paper it would 
doubtless have been immediately consigned to the rubbish 
heap, but being made of silver it was naturally laid aside 
34 


ON SILVERED PLATES 


in a cupboard to be repolished and again prepared for a 
fresh exposure. How many of us would have lost heart 
at this point and abandoned the whole affair as a practi¬ 
cal impossibility! Not so with the indefatigable Daguerre. 
It was no light task to repolish the silver plate; it re¬ 
quired great skill and care. I fancy that Daguerre must 
have come forward to open his cupboard next morning 
with a feeling of dogged perseverance; nothing for it but 
to “ try, try, try again.” Imagine his surprise, when he 
took the spoilt plate from the cupboard, to find an ex¬ 
quisite picture upon it. Doubtless he questioned whether 
he was waking or dreaming; it was too like a fairy tale. 
A perfect picture ! Nothing approaching it had ever been 
seen by man before. Wherein could lie the magic power 
of his cupboard ? Will another short exposure in the 
camera—another twenty-four hours of imprisonment in 
the cupboard—present him with another “ perfect pic¬ 
ture”? I very much doubt if Daguerre slept the follow¬ 
ing night. At any rate, there would be no chance of 
his sleeping on and failing to remove the second plate 
on the expiry of twenty-four hours. Another picture 
did appear, and equal in every way to the first, 
and so it only remained for Daguerre to discover wherein 
lay the magic of his cupboard. It was clear that the 
plate must have been affected by vapours from some of 
the chemicals in the cupboard, and so a little patience 
would be required to find out which particular dish of 
chemicals was the “ good fairy.” I think that the one 
which did prove itself to be the magical one was probably 
one of the last that Daguerre would have suggested. It 
was a simple dish of that bright semi-liquid metal known 
35 


EARLY PHOTOGRAPHS 


as mercury. In this way Daguerre discovered that if what 
he had previously considered to be a very much under¬ 
exposed plate was exposed to the vapour of mercury, the 
invisible image was gradually built up into a visible 
picture. What really happened was that the mercury 
vapour attached itself to the sensitive plate in exact pro¬ 
portion to the amount of light which had previously 
affected the plate while in the camera. 1 

Here we have the sensitive plate receiving a latent 
image, which only appears when chemically developed. 
To the photographer of to-day this has ceased to be a 
marvel, but to Daguerre and his compatriots it was 
indeed a true romance. The whole world was interested. 
It is difficult for us fully to realise their surprise. The 
wonderfully faithful picture produced by the new art was 
described by one French journal in this fashion: “In a 
view of Paris we can count the paving-stones, we see the 
dampness produced by rain; we can read the name on a 
shop.' 1 Indeed, the pictures were so good that many 
thought that all artists must pack up their paint-boxes and 
learn some other art. We are somewhat surprised to find 
the great historical painter, Paul Delaroche, sharing in this 
idea. When shown one of Daguerre’s pictures he ex¬ 
claimed, “Painting is dead from to-day.” Little could 

1 It has been questioned whether this effect could be produced by 
mercury at ordinary temperatures. One physicist assures me that 
mercury does give off a vapour at ordinary temperatures, and that he 
believes there would be sufficient to account for Daguerre’s accidental 
experiment. We must remember that the plate was exposed for 
about twenty-four hours to the influence of the mercury. If any one 
doubts the possibility of mercury at ordinary temperatures being able 
to account for Daguerre’s historical discovery, then we have only to 
imagine that the temperature of his cupboard was more than 
ordinary. 


36 


ON SILVERED PLATES 


they then foresee that photography would prove a most 
useful handmaiden to the art of painting. 

Despite all the good things that were said of the new 
art, the Parisians seem to have had no great hope of its 
commercial success, for when Daguerre tried to form 
a company to work his invention, he completely failed to 
float the shares. No doubt it seemed to be too good to 
be true. It may be that even those who knew something 
of former experiments could not believe that these “ draw¬ 
ings by Nature” would be permanent, although Daguerre 
had succeeded in fixing the pictures by washing them in 
a solution of common salt. By this means the remaining 
iodide of silver which had been unaffected by the light 
was washed away, so that there could be no further 
chemical action. Sir John Herschel, the famous astrono¬ 
mer, suggested later that hyposulphite of soda was a 
better substance than common salt (chloride of soda) 
wherewith to fix the image. This “hypo” fixer has 
reigned supreme to this day. 

It is a little difficult, at first, to see how the daguerreo- 
type picture was produced. The foundation was a copper 
plate, with a brightly polished silver surface, and this was 
rendered sensitive to light by exposing it to the vapour of 
iodine, thus forming a film or coating of iodide of silver. 
If this prepared plate was exposed to the vapour of 
mercury there was no effect; but if any part of the plate 
was first exposed to light a chemical change took place in 
the iodide of silver, and the vapour of mercury would 
then adhere to those parts of the plate which had been 
acted upon by light. 

Let us follow the taking of a portrait. The photo- 
37 


EARLY PHOTOGRAPHS 


grapher first exposes his highly polished silvered plate 
to the vapour of iodine, and protecting this from the 
light, he places it in his camera. When he removes the 
cap of the camera lens, a good deal of light will be 
reflected into the camera from the sitter’s face, and very 
little light from his black coat. The light from the face, 
falling upon the sensitive plate, effects a chemical change 
in the iodide of silver film at that place. There being 
practically no light reflected by the black coat, the film 
will remain unaffected where that part of the image falls, 
and so on with the other parts of the picture. 

When the plate is removed from the camera, still shield¬ 
ing it from the light, it is exposed to the vapour of 
mercury. The mercury vapour attaches itself to those 
parts of the film which have been attacked by light, and 
thus the high lights or white parts of the picture are 
formed. The more the film has been affected by light the 
greater grabbing power it has for the mercury vapour. 
Those parts of the film which, like the image of the black 
coat, have not been affected by light will accept no 
mercury vapour. When the plate is then washed in 
a bath of common salt, or hyposulphite of soda, this 
unaffected iodide of silver is dissolved, leaving the founda¬ 
tion plate to show through at such places. It is this fact 
which makes it difficult to understand, at first, how the 
positive picture is obtained, for the black coat is really 
represented by a patch of brightly polished silver. This 
ought to look white, and not black. So it will, if a bright 
light is directly reflected by it, and if one holds a 
daguerreotype at a particular angle one does see the 
black coat to be white. The plate must be so placed that 
38 


ON SILVERED PLATES 


it reflects only dark objects, and then the picture is seen 
as a positive in place of a negative. A familiar illustra¬ 
tion might be drawn from the art of bookbinding. We 
often see a device in gold on a bookbinding in which 
parts of the gold are frosted and parts polished. The 
polished parts look darker than the frosted in some lights, 
and brighter in others. We therefore picture the mercury 
as frosting the polished silver. 

These early daguerreotypes were very delicate, the 
slightest touch of a finger being sufficient to spoil them. 
They were also very quickly tarnished by the atmosphere. 
These defects were in some measure overcome, at a later 
period, by a process of gilding the picture. 

Having failed to float his company, Daguerre confided 
in M. Arago, one of the greatest scientists of his time. 
Daguerre showed his pictures to this great philosopher 
and astronomer, saying that henceforth Nature would 
depict her own likeness with a pencil of light. Arago 
was astonished at the beauty of the pictures and heartily 
endorsed the hopes of the inventor. Daguerre must have 
felt from that moment that his victory was won, for 
Arago was not only a learned professor, but also a leading 
politician, being at that time a member of the Chamber 
of Deputies. Arago soon gained for Daguerre the 
interest of other men of science. As it became clear that 
this new invention would prove of world-wide interest, 
these men brought forward a Bill in the Chamber of 
Deputies, recommending the House to grant annuities to 
Daguerre and the son of Niepce. The inventors could 
not have had a more able spokesman than Arago. A 
full House had assembled to learn more of this marvellous 


39 


EARLY PHOTOGRAPHS 


discovery, and that they were impressed with Arago’s 
speech is evident, for the proposed pensions were unani¬ 
mously agreed to—six thousand francs per annum for 
Daguerre and four thousand for Niepce junior. The 
reason for Daguerre’s larger pension seems to have been 
that he agreed also to make public the methods by 
which he produced his wonderful diorama and stage effects. 

The following sentences occur in M. Arago’s address 
to the Chamber of Deputies: “ The daguerreotype 

demands no knowledge of drawing, and does not depend 
on any manual dexterity. Any one may succeed with the 
same certainty as the author of the invention. The 
promptitude of the method is perhaps that which has 
most astonished the public.” 1 

When the Bill came up before the Chamber of Peers, 
it was pointed out that if the invention were left the 
secret of an individual it would long remain stationary, 
but if presented to the world at large it would be “ ex¬ 
tended and improved by a general emulation.” Therefore 
it was argued that the Government should grant the 
pensions and make the knowledge public property. 

One condition made by the Government was that the 
inventors should make known all further improvements. 
Arago made the following reference to this in his address : 
“ The importance of this latter engagement will certainly 
not appear doubtful to any person when we inform you 
that a very slight advance beyond his present progress 
will enable Mons. Daguerre to apply his processes to 

1 Exposures had been reduced to about a quarter of an hour at 
this time, which seemed remarkably quick compared with the time 
required to paint or draw a picture. 

40 


ON SILVERED PLATES 


executing portraits from life.” We shall see from a later 
chapter that the necessary improvement was accomplished 
by an Englishman within one year from the date of 
Arago’s speech. 

All those who have written upon the history of photo¬ 
graphy agree in saying that it was a distinct condition 
with the French Government that the invention should 
be a present to the whole civilised world. Then each 
writer makes a remark to the effect that 46 notwithstand- 
standing, Daguerre took out a patent for his process in 
England.” This has always seemed to me to cast a rather 
discreditable side-light upon the character of Daguerre. 
Anxious to find if there was not possibly some mis¬ 
understanding about this, I recently paid a visit to a 
Library of Patents. At first I could not find the patent 
referred to, as Daguerre’s name does not appear in the 
index of patentees. I did not doubt that a patent had 
been taken out, and knowing approximately the date, I 
had no difficulty in finding it. It was taken out by one 
Miles Berry (a London patent agent) in his own name. 
He explains that the subject of the patent is “a com¬ 
munication from a foreigner residing abroad.” 

In another part of the text, which was evidently written 
some time after the patent was sealed, Miles Berry says: 
44 1 believe it to be the invention or discovery of Messrs. 
Louis Jacques Mande Daguerre and Joseph Isidore Niepce, 
junior, both of the kingdom of France, from whom the 
French Government have purchased the invention for the 
benefit of that country .” The italics are mine, and are 
merely to emphasise these few words. It is clear, there¬ 
fore, that “the foreigner residing abroad,” presumably 

4i 


EARLY PHOTOGRAPHS 


Daguerre himself, did not read the agreement with the 
French Government in the same way as historians have 
done since then. 

Miles Berry, who took out the patent, explains that 
he applied for it in the middle of July (1839), whereas 
the agreement with the French Government was not 
made till the following month. And further that the 
patent passed the Great Seal “on the second day of 
August, now last past, which is some days prior to the date 
of the exposition of the said invention or discovery to the 
French Government at Paris hy Messrs. Daguerre and 
Niepce .” The italics are again mine, and in seeking to 
defend Daguerre I would bring forward these two points 
which I have here emphasised. 

In a small manual written by Daguerre himself at this 
very time (1839), a copy of which we have in the Library 
of the British Museum, I find that the words used by 
Arago in his speech were these. He spoke of the inven¬ 
tion as being a present “ to the world of science and art.” 
Historians have read this to mean the whole civilised 
world, whereas it is clear that Daguerre believed it to refer 
to the world of science and art in France alone. Had the 
French Government made it a clear condition that the 
gift must be extended to all nations, they would surely 
have insisted on this English patent being cancelled. 
Instead of that the patent became a source of income, 
presumably to Daguerre, for licences were granted for the 
use of this invention, as much as one thousand pounds 
being paid for the exclusive rights in some large towns. 
The patent did not expire till the regulation period of 
fourteen years had run out. 


42 


ON SILVERED PLATES 


Following up these remarks which I have just made 
in Daguerre’s defence, I can quite imagine some reader 
wishing to cross-examine me. If Daguerre believed that 
his agreement referred only to France, why did he take 
out a patent in England alone P Why did he not patent 
his process in America, in Germany, and other countries ? 
I have no doubt that what induced Daguerre to take out 
a patent in England specially was that he was aware 
that he had an English rival in Henry Fox Talbot, of 
whom we shall read in the following chapter. Probably 
Daguerre believed Talbot’s process to be similar to his own. 

I quite admit that the course taken by Daguerre is 
difficult to account for, and I was not altogether surprised 
to come across the following sentence in an old pamphlet 
in the Library of Patents (London): 1 “M. Daguerre 
himself, very reluctantly, however, yielded to the wishes 
of his friends, and secured a patent in England, by taking 
an advantage in a peculiarity in the patent laws of that 
country, yet it has been said he often regretted it.” 

In support of Daguerre’s character I would quote a few 
sentences from the Commission’s report to the French 
Parliament regarding the proposed pensions. “ From the 
first M. Daguerre perceived that the payment of a stipu¬ 
lated sum might give to the transaction the base character 
of a sale. The case was different with a pension. Reflec¬ 
tions like these could not fail to present themselves to 
a man of his exalted character , and M. Daguerre decided 
on a pension.” (The italics are mine.) 

1 The Ambrotype Manual , by Burgess, N.Y., 1857. 


43 


CHAPTER III 


A GREAT ENGLISH INVENTOR 

How Talbot came to think of what we now call photography—His 
reasoning of the matter—His first experiments—The exposures 
required—Great hopes and a great disappointment—Another 
accidental discovery—Daguerreotype versus talbotype—Some 
of the original talbotypes still good to-day—A defect in the 
daguerreotypes—How photography got on to new lines—Scott- 
Archer’s wet plates—Dry plates—A survival of the wet plate. 

I N our imagination we have seen Niepce and Daguerre 
hard at work in France for many years, earnestly seek¬ 
ing to fix the image of the camera obscura. Did no 
British scientific enthusiast make a similar attempt ? We 
are proud to claim some part, and a very important part, 
in the invention of photography. The English enthusiast 
was William Henry Fox Talbot, who was born in the first 
year of the nineteenth century. His maternal grand¬ 
father was the Earl of Ilchester, so that Talbot’s early 
training was very different from that of Daguerre. 

Talbot was educated at Harrow, and then proceeded to 
Cambridge, where he distinguished himself as a scholar. 
He devoted some time to politics, being a member of the 
House of Commons in the first Parliament after the 
passing of the Reform Bill. Scientific investigation was 
really much more to his liking, and after two years he 
retired from politics in order to devote his time to 
science. 


44 



Two of Fox-Talbot’s Original Photographs 

Fox-Talbot invented the method of taking negatives from which any number 
of positives may be produced. The photographs reproduced above were taken 
on paper negatives, which were waxed afterwards so that positives might be 
printed through them. The upper illustration was from life. The other was a 
copy of a French engraving. (See chap, iii.) 





















































































A GREAT ENGLISH INVENTOR 


Talbot was not aware of the experiments made by 
Wedgwood and Sir Humphry Davy, although these ex¬ 
periments were made during his own childhood. How 
then did Talbot come to think of what we now call 
photography? It seems quite natural that Daguerre 
should have hit upon the idea, as he was an artist, and 
was accustomed to use the camera obscura for sketching. 
Talbot was not an artist, nor was he aware of Daguerre’s 
idea. There was, however, a small optical instrument 
called a camera lucida, by which it was supposed that even 
those who were not artists might make pictures. No dark 
chamber was required, as with the camera obscura. The 
landscape was viewed through a four-sided glass prism, 
and an image of the view was seen upon the drawing 
paper, so that the would-be artist might make his picture 
by tracing out the detail with his pencil. It may be 
pointed out here that unless one viewed the paper through 
the prism there was no image seen at all upon the paper, 
whereas the image produced by the camera obscura was 
directly projected on to the paper, and could therefore 
be seen from any point. It will be clear that the camera 
lucida would not suggest to any one to try and fix the 
picture by chemical process, for the picture was practically 
an optical illusion ; it was apparently seen upon a sheet of 
paper, upon which it did not really exist. 

Talbot made an attempt to sketch the Lake of Como, 
in Italy, by means of a camera lucida, but he found it no 
easy task. When describing this futile attempt Talbot 
writes : “ When the eye was removed from the prism—in 
which all looked beautiful—I found that the faithless 
pencil had only left traces on the paper melancholy to be- 
45 


A GREAT ENGLISH INVENTOR 


hold. I came to the conclusion that the instrument 
required a previous knowledge of drawing, which un¬ 
fortunately I did not possess.” It was Talbot’s failure 
with the camera lucida which caused him to try the 
camera obscura. Here again he found that 44 it baffles the 
skill and patience of the amateur to trace all the minute 
details visible on the paper so that, in fact, he carries 
away with him little beyond a mere souvenir of the scene 
—which, however, certainly has its value when looked 
back to in long after years.” Picture the amateur of to¬ 
day pressing the button and securing each time a beautiful 
souvenir of the place he is visiting. If we had not be¬ 
come so accustomed to photography, this would, indeed, 
read like a fairy tale. 

The quotations I am making here are from Talbot’s 
original work —The Pencil of Nature —which was pub¬ 
lished in 1844. He tells us there that it was 44 the 
inimitable beauty of the pictures of Nature’s painting 
which the glass lens of the camera throws upon the paper 
in its focus—fairy pictures, creations of a moment, and 
destined as rapidly to fade away ”—it was the beauty of 
these pictures which led him on towards the great goal 
which he ultimately reached. He reflected how very 
charming it would be if these pictures would but imprint 
themselves upon the paper. The thought was quite 
original in the mind of Talbot. He asked himself why 
should this entrapping of the picture in the camera 
obscura not be possible. His reasoning of the matter is 
very interesting. He argued that if you divest the 

1 Talbot evidently placed a piece of tracing paper in the focus of 
the camera, this corresponding with our ground-glass screen. 

46 


A GREAT ENGLISH INVENTOR 


picture of the ideas which accompany it, and consider 
only its ultimate nature, it is but a succession or variety 
of stronger lights thrown upon one part of the paper and 
of deeper shadows on another. He therefore thought the 
matter out in this fashion. Light can exert an action, 
and in certain circumstances it does exert one sufficient 
to cause actual changes in material bodies. If he could 
only prepare a paper in some manner so that it would 
be acted upon by light, and visibly changed by light 
falling upon it, might he not then hope that the varie¬ 
gated scene of light and shade would leave its image or 
impression behind ? 

At the time when these thoughts occurred to Talbot— 
in 1833—he happened to be on a visit to Italy, so that 
he could not conveniently make any experiments. How¬ 
ever, he made a careful note of the matter, and of such 
experiments as he thought would be most likely to realise 
his ideal, if it were indeed possible. Although Talbot 
did not know at this time of the experiments made by Wedg¬ 
wood and Davy, he had read in chemical books that the 
nitrate of silver was a substance peculiarly sensitive to the 
action of light, and from the outset Talbot seems to have 
builded his hopes upon this silver salt. The one fear he had 
was lest this action of light upon the silver nitrate might 
not be rapid enough for his purpose. He had no idea as 
to whether the action was a rapid or a slow one, and upon 
the rapidity of the action he felt his success would 
depend. If the action turned out to be a very sluggish 
one, then his whole idea might remain a mere philosophic 
dream. 

On returning home, in 1834, Talbot hastened to put 
47 


A GREAT ENGLISH INVENTOR 


his theory to the test. Taking a sheet of white paper, 
he carefully brushed it over with a solution of nitrate of 
silver, and then exposed the prepared paper to sunlight. 
Alas! his hopes fell, for the action of the light proved 
to be very much slower than he had anticipated. Then he 
tried chloride of silver—it proved no better. However, 
instead of simply brushing the surface of the paper with 
a solution of chloride of silver, he tried to form the 
chloride on the paper. He first of all brushed the paper 
with a solution of common salt, the chemical name for 
which is chloride of sodium. He then brushed it over, 
when dry, with a solution of silver nitrate, which allowed 
chloride of silver to form on the paper. An exposure of 
this paper to sunshine seemed to give no better result. 
It so happened, however, that on one trial with paper 
prepared in this fashion Talbot observed that some parts 
of the paper blackened very much more quickly than 
others. These places seemed to be mostly around the 
edge of the paper, and with considerable patience he was 
able to analyse the cause. The most sensitive parts were 
apparently those which had been least wetted by the 
common salt. This could readily be proved. He tried a 
much weaker solution of salt, and then applied the silver 
nitrate. He was delighted to find the whole surface of 
the paper blacken uniformly and rapidly. Indeed, he 
found that too strong a solution of salt was so destructive 
of rapid change that he afterwards used salt to fix his 
pictures when taken. By washing them in a strong solu¬ 
tion of common salt he was able to prevent any further 
chemical action. 

Up to this point Talbot seems to have contented him- 

48 


A GREAT ENGLISH INVENTOR 


self with simply exposing the prepared papers directly to 
sunlight. With this new paper he found it an easy matter 
to take an impression of any flat objects, such as leaves, 
lace, etc., by merely laying these objects upon the sen¬ 
sitised paper. No doubt many of us have recollections of 
amusing ourselves when children by making impressions 
of ferns, butterflies’ wings, etc., by placing these objects 
in a photographic printing frame between a piece of clear 
glass and a piece of ordinary photographic paper. 

Talbot would, doubtless, hasten to try his new paper in 
a camera obscura. The result was, however, very far 
short of what he had expected. Even when he exposed 
the paper for “ a moderate space of time ”—by which he 
meant an hour or so—“ the outline of the roof and chim¬ 
neys against the sky was marked enough; but the details 
of the architecture were feeble, and the parts in shade 
were left either blank or nearly so.” It was evident he 
must seek some chemical preparation much more sensitive. 
It was many months before Talbot had an opportunity of 
experimenting, but in the interim he had, no doubt, given 
the subject much patient thought. I do not wish, how¬ 
ever, to weary the reader with too much detail, and as the 
further experiments which Talbot made on this occasion 
did not enable him to reach his goal, I shall pass them 
over. 

In the following summer (1835) this patient experi¬ 
menter was able to improve matters considerably by giving 
his paper alternate washings of salt and silver, and then 
exposing the paper in a wet state in the camera obscura. 
By such means he was able to reduce the time of exposure 
to ten minutes on a bright day. However, his ideal 


D 


49 


A GREAT ENGLISH INVENTOR 


seemed still very far from being attained, and for the next 
three years nothing further was done for want of sufficient 
leisure to experiment. 

Hope was revived at the close of 1838, when Talbot 
hit upon an entirely new fact. In some earlier experi¬ 
ments he had used iodine to form iodide of silver on his 
paper, but the result was a failure. It so happened in 
1838 that he had spread a piece of silver leaf on a pane 
of glass and thrown a particle of iodine upon it, where¬ 
upon he observed coloured rings form themselves on the 
silver around the particle of iodine. It was evident that 
these rings must be layers or films of iodide of silver. 
Talbot’s astonishment was far greater when, on bringing 
the plate to the window, he found the rings to change 
colour and to assume unusual tints. It would be of 
interest to see if this effect was a lasting one, or if per¬ 
chance some further change would take place, and so 
Talbot laid the plate aside for a time. We can see that 
Talbot was getting on to the very lines upon which 
Daguerre met with success—a silver surface treated with 
iodine. Whether or not Talbot’s next experiment might 
have been on these lines can only be a matter of specula¬ 
tion, for at this point the plucky toiler got a sore dis¬ 
appointment. His hope of being the first to announce to 
the world the existence of a new art, which has since been 
named photography, was completely shattered. In the 
opening days of January, 1839, Daguerre’s great discovery 
was made public. In the same month Talbot made his 
discovery known through the illustrious Michael Faraday, 
of electrical and chemical fame. Professor Faraday inti¬ 
mated the discovery at a meeting of the Royal Institution, 
5o 



Negative and Positive 

The upper illustration is a reproduction of the negative obtained by the camera. The 
lower illustration is of a photographic print from the same negative. Black and white in 
the negative appear white and black respectively in the positive. It will be observed that 
the right-hand of the negative is the left-hand of the positive. (See chap, iii.) 


















































A GREAT ENGLISH INVENTOR 


London, and a few days later the full details of the pro¬ 
cess were given, the communication being made under the 
title of “Photogenic Drawing.” This communication 
was therefore made more than six months before Daguerre 
gave the details of his process to the public. The two 
processes were, of course, on quite different lines. In 
one direction Talbot's invention far surpassed that of 
Daguerre's: Talbot gave us a negative from which any 
number of copies might be made. 

It was only shortly before this time that Talbot came 
to hear of the early experiments of Wedgwood and Davy. 
Talbot expressed great surprise that these interesting 
experiments had been allowed to fall into oblivion for 
practically a whole generation. However, there was 
nothing new for Talbot to learn from these experiments; 
he had already far surpassed them. 

It will be remembered that Daguerre's success depended 
very much on the lucky “ accident ” of the magic cupboard. 
Some years later Talbot too was fortunate enough to fall 
in with an “ accident ” of a somewhat similar, though less 
romantic, nature. One of his exposed papers happened 
to come in contact with a solution of nut-galls (gallic 
acid), whereupon he found his picture to be vastly im¬ 
proved in detail. In this way it was found that a short 
exposure in the camera, producing only a latent or hidden 
image, could be developed by an application of gallic acid. 
The result which Talbot got from this latent image when 
developed was what we call a negative bright objects 

1 It was Sir John Herschel who first used the words negative and 
positive in connection with photography. The photographic plate 
when developed is indeed a true negative—white being represented 
by black, and black by white. 

5i 


A GREAT ENGLISH INVENTOR 


.appear as black, and shadows are represented by clear 
parts. (See illustration, facing p. 50.) 

It turned out to be very convenient that the resulting 
picture was a negative, for it was possible to produce 
any number of positives by ordinary contact printing. It 
was necessary for Talbot to wax his paper negative to 
make it translucent. Sir John Herschel suggested the 
use of glass as a foundation for the sensitive chemicals, 
but it was found difficult to form the silver compounds on 
the glass. 

Talbot named his new process Calotype (beautiful 
picture), but it was also called Talbotype , in honour of 
the inventor. Talbotype and daguerreotype were rival 
processes. One would expect to find that the professional 
photographers had preferred to practise the talbotype 
process, so that they might be able to give their patrons a 
number of copies of a photograph from one negative. 
However, it was not so: the majority of the professionals 
preferred the daguerreotype, despite its one copy only. 
This was probably because the detail in the daguerreotype 
was more perfect, and possibly because a portrait on a 
“silver plate 11 could command a larger price. Talbot’s 
process was more popular among amateurs, because of its 
greater simplicity. 

When Talbot published The Pencil of Nature, in 1844, 
he pasted original photographs into each copy. I thought 
it would be of interest to see how these original prints 
had stood the test of time, it being now more than the 
space of two generations since they were made. On 
examining the copy in the British Museum Library, I find 
that most of the pictures are badly faded. Another copy 

52 . 


A GREAT ENGLISH INVENTOR 


in the Euing Collection at the University of Glasgow 
happens to be in a much better state of preservation. 

Looking down the list of illustrations, I was surprised 
to find “A Scene in a Library.” Curious to see how Talbot 
managed an interior, I turned up the illustration, to find a 
photograph of two rows of books on shelves, presumably 
in an open book-case. Some of Talbot’s pictures are 
splendid in detail; they are all of much interest. In 
showing a photograph of a haystack with a ladder leaning 
against it, Talbot remarks that no artist would trouble to 
reproduce all the detail given by the camera; it would 
indeed be impossible. 

In the accompanying illustrations facing page 44 I have 
reproduced two of Talbot’s original photographs, which 
he took himself some sixty-five years ago. These I have 
photographed from the copies pasted into The Pencil of 
Nature by Talbot. The upper illustration is entitled 
“ The Ladder,” and I think it will be of interest to re¬ 
produce Talbot’s own article published along with this 
picture. 

44 Portraits of living persons and groups of figures form 
one of the most attractive subjects of photography, and I 
hope to present some of them to the Reader in the pro¬ 
gress of the present work. 

46 When the sun shines, small portraits can be obtained 
by my process in one or two seconds, but large portraits 
require a somewhat longer time. When the weather is 
dark and cloudy, a corresponding allowance is necessary, 
and a greater demand is made upon the patience of the 
sitter. Groups of figures take no longer time to obtain 
than single figures would require, since the Camera depicts 

53 


A GREAT ENGLISH INVENTOR 


them all at once, however numerous they may be: but at 
present we cannot well succeed in this branch of the art 
without some previous concert and arrangement. If we 
proceed to the City, and attempt to take a picture of the 
moving multitude, we fail, for in a small fraction of a second 
they change their positions so much as to destroy the 
distinctness of the representation.” 

Then, referring to the possibility of taking family 
groups, Talbot adds: “ What would not be the value to 
our English Nobility of such a record of their ancestors 
who lived a century ago? On how small a portion of 
their family picture galleries can they really rely with 
confidence ? 11 

I observe that despite Talbot’s remark in this article 
that he hoped to present a number of portraits with 
The Pencil of Nature , he has only one other picture con¬ 
taining persons, and that out of thirty-one photographs 
presented. 

The lower illustration (p. 44) was a photograph taken 
by Talbot to show how engravings, etc., might be faith¬ 
fully reproduced by photography. Little did Talbot 
think that the mechanical printing-press would, some day, 
reproduce this photograph of his by the thousand. I 
think I cannot do better than quote Talbot’s own words 
concerning this photograph. 

“We have here a copy of a Parisian caricature, which 
is probably well known to many of my readers. 

“All kinds of engravings may be copied by photo¬ 
graphic means; and this application of the art is a very 
important one, not only as producing in general nearly 
facsimile copies, but because it enables us at pleasure to 
54 


A GREAT ENGLISH INVENTOR 


alter the scale, and to make the copies as much larger or 
smaller than the originals as we may desire. 

“The old method of altering the size of a design by 
means of a pantagraph, or some similar contrivance, was 
very tedious, whereas the photographic copies become 
larger or smaller, merely by placing the original nearer to 
or farther from the Camera. 

“ The present plate is an example of this useful applica¬ 
tion of the art, being a copy greatly diminished in size, 
yet preserving all the proportions of the original.” 

There was one defect in daguerreotypes which did not 
occur in Talbot’s pictures. It will be observed in the 
left-hand illustration (p. 30), by the aid of a magnifying 
glass, that the letters on the base of the pedestal of the 
monument are printed backwards. Everything was reversed 
as far as right and left was concerned. It will be obvious 
that Talbot’s negatives must have been similarly re¬ 
versed, as is demonstrated by the ordinary negative shown 
facing page 50. This reversal on the negative is very 
convenient, for when we make a positive from it there is 
another reversal, and, as we all know, “ two negatives make 
a positive.*’ In looking at the illustration (p. 50) one 
must remember that the two pictures were lying face to 
face when taken from the printing frame. 

In the centre of this photograph, which I have used to 
illustrate a negative and a positive, there will be seen 
a very high monument. This is a monument of Sir 
Walter Scott, and there is a strange story told concerning 
it. It is generally believed that the sculptor made a mis¬ 
take in putting the plaid upon the right shoulder in place 
of the left, and that when this was pointed out to the 
55 


A GREAT ENGLISH INVENTOR 


sculptor he took his own life. There have been many de¬ 
bates concerning the truth of this story. Some writers 
have argued that the Lowland shepherd often wore his 
plaid upon the right shoulder. I have been in correspon¬ 
dence with two of the best authorities on such matters, 
and both agree that the sculptor made a mistake in plac¬ 
ing the plaid upon the right shoulder. The latter part of 
the story, fortunately, is not correct. The sculptor did 
not take his own life when this was pointed out. He was 
dying of consumption all the time he was working at 
this monument, and he died before it was set up. My 
reason for mentioning this matter here is because I have 
sometimes wondered if this sculptor was led astray by 
some daguerreotype of a Highlander, in which the plaid 
would appear to be upon the right shoulder. I have 
beside me a daguerreotype of a monument of Perseus, in 
which he wields his sword with his left hand. There 
cannot have been any daguerreotypes of Sir Walter Scott 
himself, as the great author died just at the time when 
Daguerre was hard at work trying to fix the image in the 
camera obscura. 

Although some photographic studios were opened in 
1840, photographs remained curiosities till 1853. During 
the intervening time Daguerre’s and Talbot’s processes 
were rival ones, but both were to be totally eclipsed by 
a new process. Daguerre’s English patent expired at this 
time, and Talbot’s claim that the new process was an 
infringement of his calotype was defeated, so that the 
whole field was left free. 

How did photography get on to new lines at this time? 
We do not associate the peaceable art of photography 

56 


A GREAT ENGLISH INVENTOR 


with the manufacture of deadly explosives, and yet there 
is an intimate connection at this point. A Swiss chemist 
had discovered that if ordinary cotton wool was immersed 
in a mixture of nitric and sulphuric acids, it became 
highly explosive. It was found to be many times more 
explosive than gunpowder, and it became known under 
the title of gun-cotton. A little later there was a sub¬ 
stance produced by dissolving gun-cotton in a mixture of 
ether and alcohol. The resulting material was called 
collodion, being so named from its adhesive qualities. 
Collodion was very soon used in surgery to form a film 
over wounds and thus prevent contact with air. 

Several scientists suggested that collodion might be 
used for holding the chemicals on the photographic 
plate. It remained, however, for a London sculptor— 
Frederick Scott-Archer—to bring these suggestions into 
practical form. 1 Archer had been using photography for 
taking pictures of his sculptures, but after bringing out 
his collodion process he set up a photographic business. 
His place of business was in the same street as that from 
which this book is being published—Great Russell Street, 
London. Archer made his process known in 1851, but 
he did not take out any patent. Unfortunately his 
inventions brought him no wealth, and after his death it 
was found necessary to assist his widow and children. 

The collodion process quickly displaced daguerreotype 
and talbotype, and, indeed, made photography a popular 

1 Scott-Archer’s collodion process will be explained later in con¬ 
nection with the making of photo printing blocks, for which the wet 
collodion process is still used. The collodion not only acts as a 
support for the chemicals, but assists in the decomposing action of 
light. 


57 


A GREAT ENGLISH INVENTOR 


art. It was necessary, however, that these collodion 
plates should be exposed in the camera while the 
chemicals were moist. A further disadvantage was that 
they had also to be developed before the chemicals dried. 
These disadvantages would, of course, not be so serious 
to the professional photographer in his studio. To the 
amateur or the professional desirous of taking landscapes, 
etc., the difficulties became greater. We have records of 
some early enthusiasts carrying their chemicals and a 
barrel of water up mountain sides and so on. 

Some chemists succeeded in arranging the chemicals so 
that the plates might remain moist and sensitive for a 
week or more. A few years later it was found possible to 
make a plate which would remain sensitive when dry. 
Improvements in the making of dry plates soon followed. 
Gelatine was substituted for the more dangerous collo¬ 
dion, and the silver salts were dissolved in the gelatine. 
The pictures produced on the old-style wet collodion 
plates have, however, never been surpassed, and this pro¬ 
cess is still used for special purposes, as we shall see when 
we come to consider the making of book illustrations. Scott- 
Archer’s collodion process may be said to form the basis 
upon which all present-day photographic plates are made. 

We still have a survival of the wet-plate process at 
country shows, etc. We may enter the tent of the 
itinerant photographer, have our photographs taken, and 
handed to us in a few minutes. These pictures are on 
thin sheets of black or chocolate-coloured enamelled iron. 
The photographer can only give us one copy for each 
exposure. It is really a negative that is taken, and it is 
converted into a positive in the following manner. 
58 




















A GREAT ENGLISH INVENTOR 


During the process of development some chemicals are 
added to make the film remaining upon the plate white 
instead of black, as it would otherwise be. Then where 
there is no film remaining the black enamelled plate is 
seen. In this way a negative is transformed into a posi¬ 
tive. These pictures have been called tintypes , or by 
some people “ tin photographs.” One occasionally finds 
at international exhibitions some ingenious automatic 
machines which take photographs upon this tintype prin¬ 
ciple. These tintypes are merely an application of Scott- 
Archer’s process, and, indeed, the inventor himself very 
often transformed his glass negatives into positives. 
During development he whitened the black film, and then, 
in order to convert the transparent parts into black, he 
painted the back of the glass plate with black varnish, 
thus making the negative a positive. This, however, was 
of small importance compared to the larger use of the 
plate as a negative from which any number of positive 
prints might be produced on photographic paper. 

One occasionally comes across specimens of these glass 
positives at the present day. Indeed, when I set about 
making inquiries for some good daguerreotypes, with the 
object of reproducing them in the present volume, I was 
repeatedly offered “good daguerreotypes” which turned 
out to be glass positives made on Scott-Archer’s plan. 
The illustration shown facing page 58 is a photograph of 
one of these glass positives. I merely remark this in passing, 
as my object in showing this illustration is its connection 
with the photographing of criminals. The illustrations 
facing page 80 are from real daguerreotypes, and these are 
by far the best specimens I have been able to find. 

59 


CHAFTER IV 


INSTANTANEOUS PHOTOGRAPHY 

A really trying ordeal—Were the early portraits “speaking like¬ 
nesses ” ?—More about Arago’s speech—A London science lec¬ 
turer’s discovery — The origin of cartes-de-visite —An interesting 
experiment at the Royal Institution—Photographing by the light 
from an electric spark—Instantaneous shutters—Photographing 
animals in motion—The Zoetrope suggests the cinematograph— 
Great scenes lived over again—How the photographs are taken 
and the pictures reproduced—The cinematograph in the future. 

S OME of us still consider it quite an ordeal to have 
our photographs taken professionally, but what 
should we have said had our experience been that 
of one of the first victims ? Imagine the photographer 
calmly painting your face white, while he informed you 
that the flesh did not reflect sufficient light to affect the 
chemicals on his photographic plate. Even that trial 
would sink into insignificance when you were boldly 
informed that you must sit perfectly still for about twenty 
minutes. The tormentor was merciful enough to allow 
the sitter to keep his or her eyes closed. Indeed this was 
a necessity, for the full sunlight was to be reflected on to 
the face. The photographer seems to have had some 
passing thought of his patient’s comfort, for he passed the 
sunlight through a glass tank containing a solution of 
blue-stone (copper sulphate) in order to absorb the heat 
rays. 


60 


INSTANTANEOUS PHOTOGRAPHY 


During the twenty minutes—it would seem like hours 
•—through which the painted subject sat motionless, the 
photographer seems to have busied himself arranging that 
any white parts of the dress did not remain too long 
exposed to the light. He was mindful of what he 
termed “temporary expedients.’'’ 1 For instance, his in¬ 
structions were: “ A person dressed in a black coat and 
open waistcoat of the same colour must put on a tem¬ 
porary front of a drab or flesh colour, or, by the time 
that his face and the fine shadows of his woollen clothing 
are evolved, his shirt will be solarised, and be blue, or even 
black, with a white halo around it.” 2 

If we picture the poor sitter with white face and closed 
eyes, we cannot imagine that the resulting picture would 
be a “speaking likeness.” I fancy these first portraits 
must have been rather suggestive of some dear departed 
friend , and one is not surprised to find among the instruc¬ 
tions that “ the hands should never rest upon the chest,” 
although the reason assigned for this is that “ the motion 

1 The quotations regarding these early attempts at portraiture will 
be found in the London and Edinburgh Philosophical Magazine for 
September, 1840. These early portraits were taken by Dr. Draper, of 
New York, and while he found twenty minutes’ exposure necessary, it 
is asserted by a relative of the gentleman, who was the first to be 
photographed by Daguerre himself, that the old gentleman had to 
undergo the trying ordeal of one hour’s exposure in sunlight. 
Imagine sitting motionless for the space of one hour to have one’s 
photograph taken ! 

2 This question of solarisation has been of interest from the earliest 
days of photography. The chemistry of the subject is beyond the 
scope of this book, but it may be stated that solarisation is destruc¬ 
tion of the image by over-exposure, followed by reversal of the image. 
In this way the image of the white shirt on the daguerreotype be¬ 
comes very white and then gradually turns darker and ultimately 
appears black. 


61 


INSTANTANEOUS PHOTOGRAPHY 


of respiration disturbs them so much as to bring them 
out of a thick and clumsy appearance, destroying all the 
representation of the veins on the back, which, if they 
are held motionless, are copied with surprising beauty.’ 1 

Despite the remark I have just made, that the portraits 
cannot have been “ speaking likenesses,” it is quite evident 
that the photographer did aim at having his pictures true 
to life. In the description of a special chair arranged 
with a staff’, terminating in an iron ring, for supporting 
the head, I find the following note: “By simply resting 
the back or side of the head against this ring, it may be 
kept sufficiently still to allow the minutest marks on the 
face to be copied.” It is obvious that there was to be no 
retouching. How far we have fallen away from this ideal 
may be judged by the following incident. A lady, having 
had her photograph taken by one of our leading photo¬ 
graphers, handed a copy of it to a lady friend. The friend 
admired it; “ Simply charming, it is quite a picture; but 
do I know the lady ? ” 

The early attempts at portraiture, to which I have 
referred, were made in New York by the daguerreotype 
process. This process was more widely used in America 
than in Great Britain. I wonder what the early photo¬ 
grapher would have said had one of his sitters suggested 
that photographs should be taken instantaneously. No 
doubt he would have replied that such a thing would be 
an utter impossibility. 

In connection with the modern facilities for amateurs 
taking instantaneous photographs—or snapshots—it is of 
interest to note the following sentence, which is taken 
from M. Arago’s address to the Chamber of Deputies, 
62 


INSTANTANEOUS PHOTOGRAPHY 


when claiming a pension for Daguerre and Niepce. 
Speaking of the time required to take a photograph by 
Daguerre’s process, he mentions from about half to three- 
quarters of an hour; he then adds the following : “ Those 
persons are deceived, then, who suppose that during a 
journey they may avail themselves of brief intervals while 
the carriage slowly mounts a hill to take views of a 
country.” The amateur may now snap off a dozen photo¬ 
graphs in a few minutes, while he walks or drives. It 
should be noted that when Arago mentioned from a half 
to three-quarters of an hour, he did not refer to the time 
of exposure alone, but to the time spent in preparing the 
plate, adjusting the camera, and finally developing the 
image, these operations having to be performed on the spot. 

Referring again to that part in Arago’s speech where he 
said that a slight advance on the progress Daguerre had 
then made would enable him to execute portraits from 
life, I have already pointed out that the necessary improve¬ 
ment was made by an Englishman. It was a science 
lecturer in London, John Frederick Goddard, who found a 
means of making the plate sufficiently sensitive for this 
purpose. He accomplished it in this wise. Taking one 
of the daguerreotype plates which had been exposed to 
the vapour of iodine in the regulation manner, he further 
exposed it to the vapour of bromine, a non-metallic element 
whose name signifies a disagreeable odour (Greek bromos ). 
Goddard found that the plate thus treated was rendered 
so sensitive to light that an exposure of twenty seconds 
was as effective as an exposure of as many minutes on 
Daguerre’s ordinary plates. Here indeed was an immense 
improvement, which was accomplished in the year 1840, 

63 


INSTANTANEOUS PHOTOGRAPHY 


just about twelve months after Arago's eloquent address 
to the French Chamber of Deputies. Photographic studios 
were soon opened in all large cities, and the well-to-do 
citizens willingly paid as much as six guineas for a single 
daguerreotype portrait. Alas! their descendants have 
treated many of these fine works of art with scant respect, 
having often given them as playthings to children. The 
early attempts at portraiture in America, already referred 
to, were, of course, prior to this discovery of Goddard's. 

There is one term in connection with portraits which 
has an interesting origin. We are no doubt all familiar 
with that size of portrait which is called carte-de-visite, 
although one does not hear of it so often now; larger 
photographs being more common. The old portrait 
albums were made to hold these small cartes-de-visite , and 
I can remember, when a boy, wondering at so curious a 
name. There seemed to be no possible connection between 
these portraits and visiting cards, and yet there was an 
intimate connection originally. In the year 1857 the 
Duke of Parma had his portrait gummed on his visiting 
card in place of his name. The photographer to the 
Court of Napoleon III brought this idea into fashion in 
Parisian society, so that every person presented his friends 
with his carte-de-visite. No doubt these original portraits 
were somewhat smaller than those we remember under 
this title. 

Our English inventor, Henry Fox Talbot, made a very 
interesting experiment in instantaneous photography as 
early as 1851. This he performed at a meeting of the 
Royal Institution (London), and afterwards gave an 
account of it in the Athenaeum , December 6, 1851, 
64 



<05 ^ 


Photo by 


R. Brinkley and Son , Glasgow 


The Zoetrope 

This ingenious toy, which is perhaps better known as the wheel, of life, was the fore¬ 
runner of the cinematograph. The arrangement of the pictures will be seen from those 
lying upon the table. (See chap, iv.) 














































































































































INSTANTANEOUS PHOTOGRAPHY 


Taking a newspaper, he fastened it to the edge of a wheel, 
which was then set in rapid motion. The lights in the 
lecture hall were put out, the lens of the camera left open 
in the dark, and then a momentary illumination produced 
by the spark from a battery of ley den jars. The photo¬ 
graphic plate was immediately developed, and it was 
found that a faithful picture of the printed newspaper 
had been produced—“ not even a letter being indistinct.” 
This showed the specially prepared plate to be extremely 
sensitive. I wonder if it ever occurred to any of the 
many scientists present that the revolving wheel was, 
logically, only a stage effect. I do not suggest that 
Talbot intended it to be so, but if one considers the fact 
that the total period of illumination obtained from the 
electric spark was somewhere between one ten-thousandth 
and one millionth part of a second, it was surely im¬ 
material whether the wheel was revolving or standing 
still. 

Some years ago Professor C. V. Boys photographed 
flying bullets by means of an electric spark. His experi¬ 
ments will be described in a later chapter. One French 
scientist has taken a number of consecutive photographs 
of flying insects, using an electric spark as the source of 
light. In this case the experimenter used magnesium 
electrodes, between which the electric spark occurred, and 
this seems to have greatly increased the amount of avail¬ 
able light, for the prints which I have seen of some of 
these flying insects are splendidly illuminated. 

Talbot’s instantaneous process was too complex to prove 
of practical value; no one but the inventor himself ever 
succeeded in getting satisfactory results. Daguerre also 
65 


E 


INSTANTANEOUS PHOTOGRAPHY 


invented an instantaneous process which proved too com¬ 
plex and uncertain. 

The late Lord Armstrong obtained many beautiful 
photographs of electric sparks, causing them to depict 
their own images directly on to photographic plates; 
these were, of course, produced without a camera. I have 
already reproduced some of those autographs of the 
electric spark in Electricity of To-day. 

Before the days of instantaneous photography, one 
scientist used the zoetrope to enable him to reproduce 
animal locomotion. This instrument may be better 
known to some readers under the title “ wheel of life.” 
A boy is seen using the instrument in the illustration facing 
page 64. A number of pictures are painted, in succession, 
on a long strip of paper. The first picture may be of 
a boy about to jump, while in the second picture he is 
seen just leaving the ground; in the third picture he is 
in the air, and so on each picture goes until he has 
returned to the position in which he was at first. When 
this strip of paper is revolved in a cylinder and viewed 
through small open slits, one sees the pictures following 
each other so quickly that the boy really seems to be in 
motion, although his movements are somewhat spasmodic. 

An ingenious photographer arranged a whole battery of 
cameras, with which he took a number of photographs in 
quick succession of a horse in motion. He afterwards 
threw these photographs, very quickly after one another, 
upon a magic-lantern screen, and was, in this way, able to 
“ reproduce the visual appearance of horses trotting, etc.'” 

These experiments must have suggested, to many 
people, the idea of producing more perfect animated 
66 


INSTANTANEOUS PHOTOGRAPHY 


pictures. While we have in the Patent Office the record 
of one invention for this purpose—as far back as 1889— 
it was left to the great genius of Edison to place a prac¬ 
ticable apparatus upon the market, some three years later. 

I wonder what our grandfathers would have said, had 
they been present at some magic-lantern entertainment, 
when suddenly a man in one of the pictures began to 
move and to walk to and fro. Possibly they would have 
doubted their senses, or questioned whether they were 
waking or dreaming. A door in the picture opens, and in 
walks a second man, shakes hands with the first moving 
figure, and so on. How marvellous all this would have 
seemed to our grandfathers, and yet how soon do we forget 
the romance of the subject! 

Some great ceremony takes place one afternoon, and on 
the evening of the same day thousands of people see the 
very same scene most faithfully reproduced by the cine¬ 
matograph upon a lantern screen. The hero of the hour 
repeats every movement and gesture. The audience have 
an actual view of the ceremony, which is far more 
impressive than the clever word pictures of our 
journalists. 

First of all we had the kiiietoscope from Edison. This 
instrument was after the style of the old-fashioned stereo¬ 
scope boxes, and one person at a time looked through 
the eyepieces at the moving pictures. The photographs 
followed each other in rapid succession, the pictures being 
upon a long ribbon, as will be described a little later. 

A few years after the arrival of Edison’s kinetoscope 
there appeared the cinematograph, by Lumiere, of Paris, 
and also the American biograph. I only propose to 
6 7 


INSTANTANEOUS PHOTOGRAPHY 


mention the general principle upon which such instru¬ 
ments work; it is the photographic part which interests 
us at present. 

There is first of all the taking of the photographs. 
To get a really satisfactory result it was found necessary 
to take successive photographs at a rate of nearly one 
thousand per minute. It is generally believed that the 
speed is forty-six per second (2760 per minute), but 
I find that in reality the speed is only one third of that 
stated. The speed, however, will vary with different 
operators, and no doubt at times with the variation of 
subject, but for our present purpose we shall reckon the 
speed to be fifteen pictures per second. 

If photography had been confined to glass plates, the 
cinematograph would have been an impossible thing. 
Imagine trying to pass 1000 glass plates through a 
camera or a magic lantern in one minute! The intro¬ 
duction of flexible celluloid films made it possible, for the 
sensitised film could then be made in the form of a long 
ribbon. It is, of course, necessary to make the pictures 
very small, as they have to follow each other so rapidly. 
The accompanying photograph shows the actual size of 
the pictures (see facing p. 70). The progressive motions 
of the figures in the pictures will also be seen by com¬ 
paring the succeeding pictures. 

If 1000 exposures have to be taken in the camera 
every minute, it is clear that the speed must be great. 
Considering the smallness of the pictures, however, one 
finds by simple calculation that the speed of the film is 
not much more than half a mile per hour, which is about 
eight times slower than an ordinary walking pace. 

68 


INSTANTANEOUS PHOTOGRAPHY 


But while this is the rate at which the film passes through 
the camera, we must bear in mind that the motion given 
to the film is not a simple gliding one. I shall speak of 
each part of the film receiving a picture as a film. Each 
film has about one fifteenth part of a second in which to 
pass the lens, but it must not glide past. It must jump 
quickly into position and remain at rest for about nine- 
tenths of its allotted span, in order to receive the latent 
image. We may therefore picture the film resting for 
about three fiftieths of a second, and making its jump 
forward in about T t^th of a second. This means that 
the film must be jerked forward into position at a speed 
of about six miles per hour. 

The cinematograph films are wound upon brass drums, 
having very deep flanges, and one of these with a long 
film has considerable weight. Now we know that all 
bodies are very lazy about starting into motion, and equally 
lazy about stopping. This property of matter we call 
inertia. The greater the mass of the object, the greater 
the inertia. It will therefore be inconvenient to suddenly 
start and stop this drum carrying the long film. This 
difficulty is overcome by keeping the drum revolving 
constantly at the speed at which the whole film has to 
pass through the camera. Then a loose loop of the film 
is arranged between two sets of feed rollers. The parti¬ 
cular part passing between these rollers is alone given 
the sudden jerky motion. That is to say, the bulk of the 
film is travelling at a steady pace, but each portion as it 
comes between these feed rollers is jerked into position 
before the lens, an exposure made, again jerked away 
from the lens, and then proceeds again upon its even 
69 


INSTANTANEOUS PHOTOGRAPHY 


course, to be finally rolled around another deeply flanged 
drum. 

When the long ribbon film is developed, a positive 
ribbon is produced from this negative, in the same way as 
one makes ordinary magic-lantern slides. Some films 
have been made so long that it takes an hour to show 
them upon the screen, so that these films must have con¬ 
tained about 55,000 pictures. Indeed, it is very possible 
that the number considerably exceeds this, for it is 
apparent that the pictures are reproduced at a greater 
speed than that at which they were taken. Every one 
seems to be in a great hurry. Instead of quietly walking 
across a street, a man seems to be practising for a walking 
race. This quicker movement is, of course, no disadvan¬ 
tage in reproducing a horse race or any rapidly moving 
body, but I always think that our cinematograph 
friends make a mistake in rushing through the films where 
ordinary rates of locomotion are concerned. Thinking 
that there could be no optical advantage in this quicker 
movement, I inquired of one of the operators the reason 
for this increased speed. When I put a simple inquiry as 
to the rate at which the pictures were taken and the rate 
at which they were reproduced, he, at first, said they were 
at the same rate. When I pointed out that every one in 
the pictures was very energetic, he agreed that the 
pictures were being reproduced quicker, and the only 
reason was that he had to get through so many films in a 
certain time. He also agreed that if the orchestra were 
playing quick music the cinematograph operator was very 
apt to go quicker in sympathy with the music. 

The Cinematograph and Biograph Companies have been 
70 



By permission op John Trotter , Glasgow 

Cinematograph Pictures. 

The whole of these photographs will pass through the cinematograph in less than one and a 
half seconds. A subject with a very quick movement has been selected, as otherwise the 
difference between the successive pictures would be scarcely observable. Observe the right 
hand falling in the last row of pictures. (See chap, iv.) 










INSTANTANEOUS PHOTOGRAPHY 


most enterprising. They have sent representatives to all 
parts of the world. While these exhibitions cannot fail to 
fascinate us, how much greater would our interest be if 
we could see some of the stirring scenes of past centuries 
lived over again before our very eyes! When the present 
generations of men have all passed away from the stage of 
life, our distant descendants may be able still to see our 
great ceremonies, or incidents in our great battles. In 
this sense the cinematograph does for sight very much the 
same as the phonograph does for sound. We can bottle 
up our living scenes just as we may store up the songs of 
our great singers. 'When are such romances to end ? 


7 1 


CHAPTER V 


CAN WE PHOTOGRAPH IN 
COLOURS ? 


An early speech concerning colour photography—What is colour ?—A 
rather Irish explanation—A lesson from soap-bubbles—Whence the 
colours come—Our total stock of colour—Why a spectrum is 
formed—What the painter really does—The problem of colour 
photography—Taking the photographs—A simple illustration— 
Recording compound colours—Reproducing the coloured picture— 
A seeming roundabout performance—Can we call this “colour 
photography ” ?—A small instrument with a very long name—Why 
some people are disappointed with Ives’ process—Coloured pig¬ 
ments—Why call green a primary colour ?—The difference between 
mixing coloured lights and coloured pigments—A summary of 
Ives’ process—How red rays affect the plate. 

W HEN Talbot spoke of fixing the image of the 
camera obscura, he seems to have taken it for 
granted that every one understood that there 
was no fixing of the natural colours, but merely a black 
and white image. On the other hand, when the report 
upon Daguerre^ process was read before the Chamber of 
Peers (France), this matter was dealt with in the following 
words : “We hasten, however, to explain, without wishing 
in aught to lessen the merit of this beautiful invention, 
that the palette of the painter is not very rich in colour— 
black and white compose the whole. The image in its 
natural and varied colours may remain long—perhaps for 
ever—a thing hidden from human sagacity. But let us 

72 


COLOUR PHOTOGRAPHY 


not rashly circumscribe knowledge within impassable 
bournes. The successful efforts of M. Daguerre have dis- 
closed a new order of things.” 

Photography in black and white is certainly a wonderful 
invention, and has proved most useful in almost every walk 
in life. From an artistic point of view it would be a very 
much greater invention could we but fix the natural 
colours, just as we see them upon the ground - glass 
focussing screen of the camera. To fix the image in black 
and white is comparatively easy, for the picture on our 
photographic plate only requires to be made up, as it were, 
of something and nothing and a mixture of something and 
nothing. That is to say, some parts of the negative have 
a dark film remaining, while other parts have nothing, 
leaving the clear glass transparent, and the remaining 
parts of the picture come somewhere between the dark 
solid film and transparency. In this way we obtain all the 
variety of light and shade. 

When Talbot was reasoning out the possibility of fixing 
the image of the camera obscura, he said that the picture, 
divested of the ideas which accompany it, is merely a 
succession of stronger lights and deeper shadows. He 
seems to have included the sensation of colour as one of 
the ideas which accompany the picture. The fact remains 
that on the ground-glass focussing screen of the camera 
there is a picture in all its wealth of natural colours, 
while on our photographic plate and paper print there is 
nothing to stimulate our sensations of colour. Clearly to 
understand wherein the difference of these two pictures 
exists we must form a correct notion of what colour is. 

To say that colour is not a material thing is true and 
73 


CAN WE PHOTOGRAPH 


yet misleading; colour is not merely an idea. One often 
finds this subject to be a stumbling-block to the young 
mind. For instance, I remember this colour difficulty 
being brought up by some schoolgirls who had just 
returned home from a first-class boarding-school. They 
informed me that their teacher had told them that colours 
did not really exist at all; that if the girls could only see 
their dresses when hanging up in the dark wardrobe, they 
would find that the dresses had no colour. The illustra¬ 
tion, as related by the girls, was certainly rather Irish, 
and reminds one of the poor Irishman who said he had 
nothing left in his wardrobe but the armhole of an old 
waistcoat. The girls naturally reasoned the matter in 
the following manner. If there is no “red stuff 11 put 
into a dress by the dyer, then how does everybody see it 
red; it is utter nonsense to say that colour does not exist. 
Or again, when the painter paints a railing green, surely 
he puts some “ green stuff 11 on the railing. If not, where 
do the colours come from ? 

One or two simple experiments always help to make 
this question of colour quite clear to the young inquirer. 
We take a clay pipe and some soap-suds over to the 
window where we have good light. While we amuse our¬ 
selves blowing bubbles, we watch the largest ones, and we 
see that they are beautifully coloured, and that the 
colours keep changing. At one moment we see the 
bubble a beautiful red, then it changes to orange, green, 
and blue, and indeed at times it gives quite a rainbow 
effect. We know that this beautifully coloured bubble 
consists merely of some air enclosed in a thin envelope or 
film of soap and water. From whence then come the 
74 


IN COLOURS? 


colours ? They must come from the ordinary daylight 
which is falling upon the bubble ; the light must contain 
all these different colours. The sun shines into a room 
and the light strikes some cut-glass ornament, whereupon 
we find a beautiful patch of rainbow colours reflected 
upon the floor. 

Our next experiment requires an ordinary glass prism, 
which is simply a triangular piece of solid glass. In order 
to see this experiment to its best advantage we close the 
window-shutters and allow only a beam of bright light to 
enter the room. We then cause the beam of light to 
pass through the glass prism, whereupon we find the white 
light divides itself up into beautiful bands of different 
colours. At the one end we find a band of red, which 
blends into a neighbouring band of orange, and that into 
yellow, then follows green, next blue and indigo, and at 
the end a band of violet. When light is thus divided, 
analysed, or split up into its component colours, we call 
the resulting colour band a spectrum . 

I was very much interested the other day when a little 
fellow of five years of age asked me if I knew that 
red and blue made purple. When I asked him who 
had told him this, he explained that no one had told 
him, but that he had been looking at a piece of blue 
cloth through a little red glass tumbler which he had 
in his nursery, and he saw the cloth became purple. 
I told him he was quite right, and that if he took 
notice of what he saw in that way he would find a 
great deal of interest all around him. The little fellow 
was quite amused to learn that the colours really come 
out of ordinary light, and that all colours can be 
75 


CAN WE PHOTOGRAPH 

made by mixing three primary colours— red , green , and 
violet . 

In the spectrum of sunlight, more often spoken of as 
the solar spectrum, we find not only these three primary 
colours, but orange and yellow, occurring between the red 
and green. Then between the green and the violet we see 
blue and indigo colours. 

It so happens that as far as our colour sensation is con¬ 
cerned we can produce orange and yellow by blending 
red and green lights together, and we can produce blue 
and indigo by blending green and violet lights together, 
so we may say that our whole stock of colour is red , 
green , and violet . If we have three lights of these 
colours we may produce every other variety of colour. 
I shall therefore speak quite freely of red, green, and 
violet as our sum total of colour. 

We have seen the glass prism analyse sunlight and dis¬ 
play the wealth of colour of which it is composed, but 
how does a simple piece of triangular glass manage to do 
this ? It is difficult to find any very helpful analogy. If, 
however, we remember that each colour is a series of 
waves or vibrations in the ether, 1 and that the difference 
between one colour and another is merely caused by the 
different rates at which the ether is vibrating, we may 
then form some conception of what happens in the prism. 
The ether may be vibrating with such a comparatively 
slow to-and-fro swing that it does not affect the sensitive 

1 The ether of space has no connection whatever with the liquid 
ether which is used as an anaesthetic. No one knows what the ether 
of space is, but it is not ordinary matter. It is a mysterious something 
which pervades all space and acts as a medium for transmitting 
light, etc. 


76 


IN COLOURS? 


retina of the eye at all, but we find a heating effect in 
such rays. When the rate of ether vibrations reaches 
a certain pitch they set up the sensation which we call 
red. If the rate of vibration is somewhat increased the 
resulting sensation is green , and with a still further 
increase of vibrating rate we have violet. If the rate of 
vibration be increased still higher, the rays fail to affect 
our eyes, but these invisible rays will affect a photographic 
plate. 

When our red, green, and violet sensations are simul¬ 
taneously excited, we have the effect of white light. 
Now when this white light falls upon a glass prism, the 
rays all meet with a certain obstruction. We may picture 
those rays with a slow rate of vibration (red) being 
deflected or refracted only a little out of their path when 
passing through the prism. The other rays (green and 
violet) are banging about, as it were, more energetically, 
and therefore suffer a greater degree of refraction, accord¬ 
ing to the rate of their vibrations. We therefore find 
the rays of different rates of vibration coming out at the 
other side of the prism at different angles. If we allow 
them to fall upon a sheet of white paper, we find the red 
rays are least bent out of their normal path, but the 
green rays being bent further fall clear of these, so that 
we have the red sensation stimulated by one set of rays 
and the green sensation separately excited, while an over¬ 
lapping of the two sensations produces the effect of orange 
and yellow. Then again the violet is more bent out of 
its normal path than the green, so that it falls clear of the 
green, and the rays from that part of the paper excite 
the violet sensation. Here again there is an intermediate 
77 


CAN WE PHOTOGRAPH 


part of the paper upon which rays fall which excite both 
the green and the violet sensations, producing the sensations 
we know as blue and indigo. 

Now it will be clear to us that if we only allow red rays 
of light to fall upon a piece of white paper or any other 
white object, that object will appear red, as it will only 
reflect red rays to our eyes. The colour is not part and 
parcel of the object. But there is another way of pro¬ 
ducing the same effect. We may apply certain chemical 
pigments to the surface of the paper or other object, so 
that when ordinary light falls upon it all the coloured 
rays are absorbed or blotted out with the exception of 
the red rays. The object only sends back red rays, and we 
again see the object red. Here again the colour is not 
part of the object, as we shall see by a very simple experi¬ 
ment. For the present we must be content to know 
that some chemical pigments absorb certain colour rays 
and send back the remainder, and that with the aid of 
sufficient variety of pigments we may so manipulate white 
light that we can produce every known colour. The 
question of colour absorption and reflection will be 
better understood when we come to consider Nature's 
camera. 

Let us take some very red object—a pure red—say the 
chemical known as bin-iodide of mercury, which has a 
bright vermilion colour. There is no mistaking the fact 
that this substance is red. We have a quantity of this 
in a glass tube or bottle, but we must be careful to have 
it well corked up, as the substance is very poisonous. We 
close the window-shutters and set a light to some methy¬ 
lated spirits and common salt, which we have previously 
73 


IN COLOURS? 


mixed in a small saucer. We now look at the red sub¬ 
stance by this light, but, alas, it is no longer red; it is a 
dirty grey. Its beauty has quite forsaken it. We ex¬ 
tinguish the artificial light and again view the substance 
by daylight—or by gaslight—whereupon its rich ver¬ 
milion colour at once returns to it. Now it is quite clear 
no chemical change whatever took place in the red sub¬ 
stance ; it was securely corked up in a glass tube or 
bottle. Why, then, did the bright red colour disappear 
when viewed by the methylated spirits light ? Simply 
because there are no red rays in that particular light, 
which is not white, but yellow, and contains scarcely any 
but yellow rays. The chemical is capable of reflecting red 
rays, but it is helpless if no red rays fall upon it. I have 
merely selected this particular chemical by way of illus¬ 
tration, as I find that it answers the experiment very well. 
We might use the red cover of a book, but it is difficult to 
get a pure red in which there is no mixture of other colours. 

When the painter makes our railing green, what he 
really does is to put on some substance which will send back 
the green rays contained in white light and absorb the 
other rays. The limelight operator at the pantomime 
may change the colours of a dancer’s dress, so that at one 
moment it appears red, at another green, or yellow, or 
blue. When he puts a red glass into the lantern he cuts 
off the green and violet rays, and allows only the red rays 
to pass out and fall upon the dancer’s dress. It must 
surely be clear to every reader that colour is not an in¬ 
herent property of the object. 

I have purposely gone into the subject of colour at 
some length, for I do not think it possible for any one to 
79 


CAN WE PHOTOGRAPH 


form a comprehensive idea of colour photography without 
first obtaining a clear understanding of what colours really 
are. There is a wide field of interest in connection with 
colour; I have only touched upon the simple phenomena 
relating to our present subject. 

It occurs to me that some reader may be wondering 
how the soap-bubble, already referred to, is able to pro¬ 
duce different colours. This will be better explained a 
little later when we come to consider the Lippmann 
process of colour photography, which is based upon the 
same phenomenon. 

Our problem is to entrap the colours as they fall upon 
the photographic plate. When we look at the image on 
the ground-glass focussing screen of a camera we see all 
the natural colours of the scene depicted there. We know 
very well that the ground-glass screen has no selective 
power for colours; it is merely reflecting whatever rays 
fall upon it from the different objects. It is the objects 
themselves which have split up the white light falling 
upon them and reflected back certain rays. How are we 
to fix these when we substitute a photographic plate for 
the focussing screen ? 

What a variety of different colours we are to entrap ! 
The little five-year-old fellow reminds us that we have 
only three colour sensations—red, green, and violet; that 
all the other colours in the picture are produced by differ¬ 
ent mixtures of these lights. Ah ! here then is one way 
of reproducing all this varied scene of colour. Let us 
first of all make the red rays alone enter the camera, and 
we shall get a negative which will be blank everywhere 
except where the red rays have fallen. Suppose by way 
80 


IN COLOURS? 


of simple illustration that we are photographing a red 
vase containing some yellow flowers and green leaves. We 
wish first of all to take a record of all the red in the ob¬ 
jects. We must let the red rays alone enter the camera. 
How can we do this ? We know that a red object will 
reflect only red rays and absorb or cut off all the other 
rates of vibration. If the red object be transparent, say 
a piece of red glass, then it will not reflect all the red 
rays as an opaque body will do, but will let some of the 
red rays pass through it. Therefore if we take a piece 
of red glass, or better still a sheet of gelatine dyed a pure 
red, and place this so that all the light entering the 
camera must pass through this red screen, what will 
happen ? The red screen will act as a filter to the light; 
it will absorb or cut off all the green and violet rays, and 
allow only the red rays to reach the photographic plate. 
It is immaterial whether we place this red screen of gela¬ 
tine before or behind the lens, or right inside the camera 
directly in front of the photographic plate; all that we 
require is that the screen should intercept all the green 
and violet rays before they can reach the sensitised plate. 

So far we have only made a negative showing the red 
objects. If we examine it we shall find that we have not 
only an image of the red vase, but also an image of 
the yellow flowers. That is to say, we have a record not 
only of the objects which appeared red, but of all the red 
rays, whether they were seen as red or blended together 
with some other rays, producing a mixed or compound 
colour. This is quite as we should expect, for we know 
that yellow is obtained by an overlapping or blending 
together of red and green. 


F 


81 


CAN WE PHOTOGRAPH 


If we now take a second negative, through a green colour 
screen, we shall have a record of all the green rays—the 
green leaves and also a fainter image of the yellow flowers 
again, as there will be green rays reflected by them. It 
will be understood that these are ordinary black and white 
negatives showing no colour. On the first negative we 
have an image of the red vase, and an image of the 
yellow flowers, but no image of the green leaves. On the 
second plate we find no vase, an image of the green leaves, 
and an image of the yellow flowers. The yellow flowers 
have affected both plates, as they reflected a mixture of red 
and green rays. 

So far we have been speaking of the red vase as though 
it were a plain red one, but let us suppose that it is of 
some Eastern style and has a blue figure upon it. We 
know that blue is a blending together of green and violet, 
so that there will be an image of the blue figure upon 
the second or green negative. To entrap the remaining 
violet rays we must take a third negative, and this time 
through a violet screen. On this third negative we shall 
only get an image of the blue figure on the vase. 

We have three different records, but we have no colours. 
We have, however, analysed our coloured objects; we 
have split up all the colours, taking a record of each 
primary colour upon a separate negative. Suppose we 
try and reconstruct our coloured picture. Perhaps the 
simplest plan will be to make a picture on the magic- 
lantern screen. 

So far we have only made negatives. Now we must 
make lantern slides in the usual way. The reason for this 
will be apparent, for if we look at the first or “ red ” 
82 



By permission oj 


the Thornton-Pickard Co., Ltd. 


Two Instantaneous Photographs 


The upper illustration is of a disused chimney-stack being demolished. The 
falling chimney appears to be stationary in mid-air, having been photographed in 
one-hundredth part of a second by means of a Thornton-Pickard focal-plane 
shutter. The lower illustration shows the attitude of a cock when crowing, and 
was taken in one-eightieth part of a second by means of a Thornton-Pickard 
time and instantaneous shutter. 












IN COLOURS? 


negative, we find an opaque image of the vase upon a 
transparent background. This is just the reverse of what 
we want for the lantern, so we take this negative and print 
a positive from it. Instead of printing a positive on to 
photographic paper, we place a second photographic plate 
behind the negative. We simply make a contact print 
from the negative on to the second plate, so that the 
dark opaque vase will now be a transparent vase upon an 
opaque background. This is just what we want for the 
lantern. 

If we now place this transparency or lantern slide in the 
magic lantern, we get a bright white image of the vase 
and flowers upon an otherwise dark sheet. If, however, 
we place a piece of red glass in the lantern, so that only 
the red rays of its light can pass out, we shall then have 
a red vase upon the lantern sheet. We shall also have 
a red image of the flowers in the vase. This red represents 
the amount of red which was reflected by the yellow 
flowers. 

What I have just described is a reproduction from the 
first or red negative which we took, but it will be re¬ 
membered that we afterwards changed our vase for a fancy 
one having a blue figure upon it. We made the green and 
violet negatives from this fancy vase, but I purposely left 
the red negative alone for the sake of simplicity. It will 
be quite apparent that if the fancy vase had been used for 
the red negative, then the blue figure would have reflected 
no red rays; and as there were only red rays entering the 
camera, we should now have on our transparency or lantern 
slide no light on that part of the vase representing the 
blue figure. I think the best way to look at the complete 
83 


CAN WE PHOTOGRAPH 


reproduction from the red transparency is this. Upon a 
dark background we have a red vase with the background 
showing through where the blue figuring should be; we 
have also red flowers representing the yellow flowers 
placed in the vase. 

In the meantime lantern slides have been prepared 
from the green and violet negatives which we took. We 
must throw a green and a violet light respectively 
through these transparencies. We have practically three 
different lanterns, one for each colour. Each lantern will 
throw upon the screen its own particular part of the 
picture; it will therefore be very necessary to have all 
three lanterns carefully focussed so that the three pictures 
exactly overlap each other. 

To continue the building up of our picture, we take 
our second transparency and throw a green light through 
it. This will add the green leaves, and also an image of 
the flowers in green, which, falling upon the faint red 
flowers, will make them appear yellow. Red and green 
lights overlapping produce the sensation of yellow. This 
fact will be easily remembered if one thinks of the colours 
in the solar spectrum; between the red and the green comes 

Our green transparency has added something more to 
the picture. There is now a green image of the figuring 
upon the fancy vase. All that remains for the violet trans¬ 
parency to do is to throw a violet image of the figuring 
upon the vase, and this overlapping the already green image 
changes it to blue as in the original vase. Think again 
of the colours in the solar spectrum : between the green 
and the violet comes blue. For any one not quite con- 

84 


IN COLOURS? 


versant with the colours in the spectrum of daylight, it 
would be a good plan to paint the colours roughly upon 
a strip of white paper. Almost any child’s paint-box 
would serve the purpose quite well. Make the red, green, 
and violet more prominent than the others, and then fill in 
orange and yellow between the red and green, and paint 
in blue and indigo between the green and the violet. If 
there is no paint-box conveniently at hand, it will be 
sufficient to write down the names of the colours in their 
proper positions; make the words red, green, and violet 
much more prominent than the others. If this strip of 
paper is kept as a book-mark it will be found very useful 
in reading the next chapter. 

Looking at the lantern sheet, we now see our complete 
picture, the red vase with its blue figuring, the green 
leaves, and the yellow flowers. What a roundabout way 
we have taken of arriving at a reproduction of our 
picture! Why not have merely taken one single negative 
in black and white and then have coloured it? This 
suggestion only arises because I have chosen an ideally 
simple illustration. I have presumed the green leaves 
to be one uniform shade of green, and the same with the 
other colours. Think rather of some scene in a conser¬ 
vatory—an indescribable variety of shades in leaves and 
flowers. Our three negatives will record the component 
parts of all these shades, and we shall be able to repro¬ 
duce these in all their delicacy far better than the artist 
can. 

Can we call this result a photograph in natural colours ? 
The “ man in the street ” says we cannot. The scientist 
may say, with some truth, that we have reproduced the 

85 


CAN WE PHOTOGRAPH 


natural colours ; we made red rays record themselves, and 
we made that record to control the red rays once more. 
Have we not reproduced colour vision just as much as the 
phonograph reproduces sound? What the public really 
mean by colour photography is that the photograph, 
when viewed as an ordinary picture, should show the 
natural colours. We have not accomplished this. 

The three-colour process, which we have been consider¬ 
ing, was devised by Frederick Ives, of Philadelphia, about 
the year 1895. The colour photographs can be shown 
not only upon a large lantern sheet, they may be viewed 
in a small instrument which is burdened with a very long 
name—the stereophotochromoscope. This is a very in¬ 
genious little instrument, which does practically the same 
as the three-lens lantern, but in a portable form. Inside 
the small box the three-colour pictures are so arranged 
that they appear as one picture when viewed through the 
two eyepieces. The natural appearance of the picture pro¬ 
duced in this long-named little instrument is enhanced 
by there being three pairs of slides, each pair producing 
a stereoscopic effect. We need not consider this part of 
the subject at present, as the principle of the stereoscope 
will be fully dealt with in a later chapter. 

I remember seeing the first stereophotochromoscope 
brought to this country, and the effects produced were 
marvellous. The instrument was shown at a meeting of 
one of our Philosophical Societies, and I can remember 
that many members were disappointed—because this pro¬ 
cess was not colour photography as they understood it. 
They wanted something one could take home and put in 
an ordinary frame or album. The results, however, were 
86 


IN COLOURS? 


none the less pleasing, and when one looked at the pictures 
in the little instrument one could easily see that no artist 
had ever painted such a variety and delicacy of tint. Of 
course it is a serious drawback that the pictures can only 
be seen when viewed in this specially arranged apparatus, 
or upon a lantern screen. 

Referring again to the simple vase of flowers, used as 
an illustration in describing Ives 1 process, it will be noted 
that we only dealt with four colours—red, green, yellow, 
and blue. It will be remembered, however, that all the 
variety of colours existing can be made up by blending 
together the three primary colours—red, green, and violet. 
Therefore every colour when filtered through these three 
colour screens will leave a record either on one, on two, or 
on the three negatives. A white object, being all three 
primary colours blended together, will affect all three 
negatives in certain definite proportions. When the 
three primary colours are again blended together by 
means of these records they will reproduce a white 
object. If one is not familiar with the results obtained 
by blending different colour rays together, all one need 
remember for our present purpose is that on the first plate 
is recorded all the red rays, on the second plate the green 
rays, and on the third plate all the violet rays. It makes 
no difference whether these rays are visible as red, green, 
or violet, or whether they are mixed up together, forming 
other compound colours. 

It must be clearly understood that all the blending of 
colours with which we have been dealing has been 
a blending together of coloured rays of light. It is usual 
to say that the mixing of coloured pigments gives quite 
87 


CAN WE PHOTOGRAPH 


different results from the mixing of coloured lights. The 
ordinary reader feels as though he had been landed in a 
fog. The statement requires some elucidation. One must 
remember that in mixing so-called colour pigments we are 
merely manipulating the colour rays present in the light 
falling upon the pigments. I shall only touch upon this 
subject very briefly at present, as a fuller explanation will 
be of more direct interest when we are considering the 
making of three-colour book illustrations. 

I feel sure that some reader has thought in reading the 
preceding part of this chapter that it seemed strange to 
speak of green as one of the three primary colours. As 
very youthful artists we may remember mixing yellow and 
blue paints together to produce green. We therefore 
have the impression that green is a compound colour, and 
not one of the three primary colours. At present we 
shall be contented with general statements, leaving the 
detail to be filled in later, as already suggested. Looking 
at our mixture of the two paints, we may imagine the 
combined efforts of the blue and the yellow pigments to 
have absorbed all the red and violet rays, leaving only the 
green rays to be reflected; we therefore see the mixture 
to be green. 

The once youthful artist says that surely a blue and 
a yellow glass, if placed together in a lantern, will also 
produce green upon the lantern sheet. Certainly they 
will; the result will be just the same as got by mixing the 
blue and yellow pigments. 1 But in making our coloured 

1 We have in the light of the lantern red, green, and violet rays, 
and these endeavour to pass out of the lantern. But the blue glass 
obstructs, or cuts off, all the red rays, and allows only the green and 
88 


IN COLOURS? 


pictures upon the lantern sheet we did not place two 
coloured glass screens together in one lantern ; we had 
a separate light for each colour. If we blend the blue 
and yellow lights together by that method, throwing the 
two separate colours directly on to the lantern sheet, we 
find that we have produced a practically white sheet. 
There is no green now. How is this, and wherein lies the 
difference ? 

The first case seems simple enough. We filtered a white 
light through both a blue and a yellow screen, placed one 
behind the other. The white light consisted of red, green, 
and violet rays, but the two screens managed to cut off all 
the red and all the violet rays, leaving only the green rays 
to pass through and reach the lantern sheet. The second 
case is different, but is also quite simple. We have a 
separate white light for each colour screen. We first of 
all throw one light, say, through the blue screen. It 
allows both green and violet rays to pass through it, 
cutting off only the red rays; we therefore see the sheet 
to be this compound colour called blue, which is due to 
the green and violet sensations being simultaneously 
stimulated. Now when we throw another separate light 
through the yellow colour filter, we allow both red and 
green rays to reach the sheet, only the violet rays being 
cut off. But we already have the violet sensation stimu¬ 
lated along with the green sensation, and if we now add 

violet rays to pass. These are encountered by the yellow glass screen, 
which obstructs all the violet rays, leaving only the green to pass out 
of the lantern. That is to say, the light in passing through the first 
screen is robbed of all its red rays, and then it is robbed of all its 
violet rays by the second screen, so that green rays only issue from the 
lantern. 


89 


CAN WE PHOTOGRAPH 


red, and more green, we have all three sensations simul¬ 
taneously excited, so that we have the resulting sensation 
of white light. 

Must we bother with all this detail concerning colour in 
a chapter dealing with colour photography P I see no 
way of forming a clear conception of the subject unless 
we are willing to take this trouble. The subject is really 
not a complex one, if we let the little five-year-old fellow 
remind us occasionally that all colour is summed up in 
red, green, and violet. 

Before closing this chapter it may be of interest to give 
a short summary of what Ives’ process of colour photo¬ 
graphy does. First of all a separate record is taken of 
each of the three different colour rays sent back from the 
objects we are photographing; not only where these 
primary colours are recognisable, but wherever they exist 
in combination with one another, forming compound 
colours. These three different records are then used to 
reconstruct the coloured picture. Each record controls the 
amount of its own colour falling upon the different parts 
of the lantern sheet. Ives only throws red, green, and 
violet lights upon the lantern sheet, but these three 
colours when recombined by the records which they 
themselves made produce upon the lantern sheet all the 
variety and delicacy of the colours in the original objects. 
Ives therefore adopts a different method from that of the 
artist when painting a picture. The artist mixes his pig¬ 
ments until they collectively cut off all the rays which he 
does not wish to be reflected from the canvas, and reflects 
only those rays, or combinations of rays, which he desires 
to stimulate our sensory organs. The artist starts with 
90 


IN COLOURS? 


one bundle of red, green, and violet rays (white light), so 
that all his manipulations must necessarily be cases of 
subtraction. Ives, however, has three separate colour 
pencils, red, green, and violet lights, which he may add 
together as he desires, and therein really lies the difference 
between blending coloured rays of light and mixing 
coloured pigments. 

Ives’ process is excellent, but it must be admitted that 
the results have taken us no nearer the public’s ideal of 
colour photography. It may be mentioned, in passing, 
that Ives has constructed a camera for taking all three 
negatives at one time. He uses only one lens, but 
separates the different rays by means of colour screens 
placed inside the camera. These three records may be 
taken upon one plate, but they still remain as three 
distinct and separate pictures on different parts of the 
plate. It is only a matter of convenience having the three 
negatives on one sheet of glass. 

Probably some readers, accustomed to photographic 
work as amateurs, may have wondered how the red rays 
have been able to make any record at all upon the photo¬ 
graphic plate. The photographer uses a red light in his 
dark room and does not hesitate to examine his sensitised 
plates in this light, knowing that the red rays will have 
no effect upon the sensitive film. How then are the red 
rays to make a record in the camera ? It is clear that we 
cannot use an ordinary photographic plate. Plates are 
specially prepared for colour photography. The chemical 
films on these plates are sensitive to red rays as well as to 
green and violet. 

Any further detail concerning this interesting and 
9i 


COLOUR PHOTOGRAPHY 

beautiful process of Ives would be beyond our present 
purpose. 

Much of the detail concerning the nature of colour, etc., 
contained in this chapter will be of service to us in the 
proper understanding of the other processes of colour 
photography which are described in the two following 
chapters. 


92 


CHAPTER VI 


MORE ABOUT COLOUR 
PHOTOGRAPHY 

A threefold record on one negative—Joly’s process—How the colouring 
is reproduced—An analogy from fancy weaving—Negative and 
positive—Another ingenious method—Why some processes do 
not use the primary colours—How the natural colours are repro¬ 
duced—The colour filters—A simple illustration—A complete 
lantern slide—Dissecting a Sanger Shepherd slide. 

I N Ives’ process, described in the preceding chapter, it 
was necessary to take three separate negatives—one 
being a record of the red rays, another of the green 
rays, and the third of the violet rays. Could we not take 
all three records on one plate as one complete picture, 
instead of having three separate pictures, each containing 
only a part of the whole ? If we have followed the 
particulars about colour in the preceding chapter, it will 
be quite clear to us that it would be useless to try and 
take a photograph through all three colour screens or 
filters at one time. Suppose we do place the three 
screens in the camera, one behind the other. The light 
entering the camera first of all meets the red screen, which 
cuts off all the green and the violet rays, and allows the 
red rays alone to pass in. These red rays are immediately 
obstructed by the green coloured screen, leaving no light 
to pass in any further. If we try any two of the coloured 

93 


MORE ABOUT 


screens we shall find that they alone are sufficient to 
obstruct all the light. No light, no photograph. 

We are quite convinced that there is no use of at¬ 
tempting to take one complete record of all three colours 
through the combined colour screens; we have seen that 
the result would be a blank. Professor Joly, of Dublin, 
however, has shown us that it is possible to get the whole 
three records in one negative by a single process. The 
method adopted is both interesting and ingenious. 
Instead of three separate colour screens—red, green, and 
violet—we take one clear glass screen and then paint thin 
lines of these colours upon it. We first of all paint or 
rule a very fine line of red across the glass plate. Right 
alongside of this we paint a green line, and next to that a 
violet line, each line touching its neighbour. Then again 
we paint another red line, and so on—red, green, violet, 
red, green, violet—until we have the whole plate covered 
with coloured lines. 

This striped screen will not cut off all the light now. 
Each line of red will allow red rays to pass through that 
line, so that a photograph of a red vase taken through 
this screen would show the image of the vase in separate 
parallel lines. The lines, however, are very close together, 
and if the picture is looked at from a little distance the 
image has the effect of being solid. The green objects 
will be recorded in similar fashion through the green lines, 
and the objects reflecting violet rays are recorded through 
the violet lines. Although the red, green, and violet 
rays have had to pass through different lines, or slits, all 
the rays have found an open door, so that the resulting 
negative contains a complete record of the objects 
94 



By permission of the Thornton-Pickard Co., Ltd. 

A Bad Fall 

Needless to say the fall was not a matter of arrangement. The photograph was taken in one seven-hundredth part 

of a second by means of a Thornton-Pickard Focal-plane shutter. 














































































COLOUR PHOTOGRAPHY 


photographed. There is, of course, no colour on the 
photographic plate; we have merely sorted out the rays 
and taken a black and white record of each colour forming 
the picture. 

In Joly’s process we have the three separate colour 
records lying in consecutive parallel lines or stripes, 
whereas in Ives’ process the three records are on separate 
plates. The taking of the Joly records is naturally a 
much simpler process, but how are we going to reproduce 
the coloured picture P We must, of course, throw red 
rays through that part of the record made by the red 
rays, and so on. This is really very simply done. We 
place the screen with the coloured lines immediately 
behind the threefold record, taking care that the red lines 
are exactly opposite the lines representing the red record, 
and similarly with the other coloured lines. We thereby 
recombine the rays and reproduce upon the lantern sheet 
all the beauty of the original delicate colouring. If one 
is close to the lantern sheet, the lines are noticeable; the 
picture appears in stripes. If one is at a little distance, 
the individual lines are not seen, so that the picture 
appears solid, and the delicacy of the natural colours is 
marvellous. 

It occurs to me that we have a good analogy of Joly’s 
process in the art of fancy weaving. The weaver desires 
to produce upon a cloth a conventional floral effect in 
which there is to be a yellow flower with a red edge sur¬ 
rounding it and a patch of green at its centre. What he 
really does is to throw first a yellow thread across his web 
with one shuttle, bringing the yellow to the surface of his 
cloth wherever he wishes it to be seen. He then throws a 


95 


MORE ABOUT 


second shuttle filled with red yarn, and after that a green 
shuttle. The weaver’s method is very similar to Joly’s 
process. The weaver has three successive lines of coloured 
yarn repeating all the way across his piece; Joly has 
three coloured lines all the way across his picture. The 
picture in each case is built up by these lines showing at 
some places and not at others. The lines follow each 
other so closely that they are not distinguishable as 
separate lines when viewed from a little distance. 

I think we may carry our weaving analogy a little 
further. If a weaver desires to make a cloth, using only 
two colours for producing the figure, he often brings in 
a third colour effect by mixing these two colours in 
a solid mass. He may make a yellow object with a blue 
edge, and then by mixing these two colours together at 
one part he produces the impression of green. Most 
of us have seen fancy looms at work at our international 
exhibitions or elsewhere, and we know that the design in 
the cloth is produced by a machine on the top of the 
loom. We need not trouble about the details of this 
Jacquard machine. It will be sufficient, for our present 
purpose, to know that it contains several hundreds of wire 
needles, which are controlled by holes punched in cards, 
and that these needles in turn control the threads of the 
warp which are stretched out in the loom below. Each 
card represents one throw of a shuttle, the warp being 
opened to let the shuttle pass through, so as to bring the 
yarn in the shuttle to the surface wherever it is wanted. 
We therefore see that the holes in one card represent the 
yellow yarn which is to show, while the holes in the next 
card represent the blue yarn which is to come to the sur- 
96 


COLOUR PHOTOGRAPHY 


face. But what about the green patch of colour? It 
must, of course, be represented by holes in both cards, as 
it is a combination of both these colours. In a similar 
sense, we must remember that when we record the red rays 
of light in colour photography we not only record rays 
from the red objects, but also from all objects whose 
colour has red rays contained in it. 

It will be quite clear to all that when the threefold 
record is taken in the camera, the developed negative will 
only show black lines of varying density wherever the 
different rays have affected the plate. In order to repro¬ 
duce the picture we wish the reverse of this, so that we 
may have, as it were, clear slits to correspond with the 
parts on which light fell. We therefore make a positive 
from this negative in the usual way, and then we can 
make light shine through those parts of the positive 
record which were affected by light on the original nega¬ 
tive. 

The subject of negative and positive is so simple to all 
those who are accustomed to photographic processes that 
it would seem quite unnecessary to refer to it again. How¬ 
ever, as I have sometimes found that the why and where¬ 
fore of this subject is not clearly understood, it is worth 
while referring to it once more. We may picturesquely 
think of the light entering the camera and attacking the 
chemicals upon the sensitive plate, and wherever it strikes, 
altering the chemical condition of that part of the film. 
On looking at the exposed plate in the “dark-room” 
we see no effect upon the chemical surface. When we 
place the plate in a developing bath the liquid soon 
darkens the chemicals which have been affected by light, 


G 


97 


MORE ABOUT 


leaving the affected parts as black patches of varying 
densities. Our negative is therefore opaque wherever it 
represents a white object, and clear glass wherever it 
corresponds with a dark object or shadow (see illustration 
opposite p. 50). This is just the reverse of what we 
wish for our magic lantern. We wish to let light shine 
through the image of a white object and obstruct the 
light by the image of a dark object. The record of our 
white object cannot therefore be opaque, but must be 
clear glass. We have no difficulty in obtaining a reverse 
of our negative. We place the developed negative with 
its picture in contact with a second sensitive plate, and 
allow light to pass through and attack the chemical film 
on the second plate. As the image of a white object is 
solid film on the first negative, that will prevent any light 
reaching the second plate at that part, so that the film 
representing this white object on the second plate will be 
left clear glass through which we can now throw the light 
of the lantern and form a bright image of the white object 
upon the lantern sheet. 

It is clear that every lantern slide of Joly’s process 
must have a ruled screen of colours bound up with it. 
Can we not dispense with this line effect and make 
a coloured lantern slide complete in itself? We shall see 
what has been accomplished. 

We return to the original Ives’ method of taking three 
separate negatives, but we wish to reproduce the picture 
by one lantern slide requiring only one light. We have 
already seen that there is no good in placing red, green, 
and violet screens together in one slide. It will be re¬ 
membered that any two of these screens placed together 
98 


COLOUR PHOTOGRAPHY 


will cut off all the light from the lantern. Each screen 
cuts off two of the three primary colours, so that any 
two of the screens will annihilate all three primaries. 
We are attempting to work on quite a different plan 
from that adopted by Ives in reproducing his pictures. 
He had three separate lights, giving red, green, and 
violet rays respectively. These he could add together at 
will by his three separate transparencies. We are now 
starting, however, with all our three colours blended 
together in one light, so we must subtract the rays we do 
not wish for from each part of the picture. If we must 
always subtract two of the colours at one time we are 
helpless; we want at some parts of the picture to sub¬ 
tract only one primary and allow the other two to reach 
the lantern sheet blended together. What we really 
want, then, is to be able to subtract each of the primary 
colours one at a time. Colour screens, or filters , have 
been made for this purpose by Lumiere (France), Sanger 
Shepherd (England), and others, who have devised a very 
beautiful process of making complete colour lantern 
slides. 

First of all we wish for a screen, or colour filter, to cut 
off only the red rays. In other words, we wish for a screen 
to permit both green and violet rays to pass. We must 
keep in mind that we are dealing with the blending 
together of coloured lights, and not with the mixing of 
colour pigments. Although it will be necessary to pre¬ 
pare dyes in order to colour the screens, or filters, we shall 
not concern ourselves with the dye stuffs. To simplify 
matters, we shall only deal with the mixing or blending 
of the coloured lights. 

99 

l, OF C. 


MORE ABOUT 


In order to make matters quite clear, it would be well 
to make a few experiments with a triple lantern such as 
is used by Ives in his process. We have three separate 
lights exactly overlapping one another upon the lantern 
sheet. Perhaps our simplest plan will be to place all 
three colour slides in the lanterns. We have a red, a 
green, and a violet light, all overlapping one another, 
and the result is that the lantern sheet appears white. 
It does seem strange that all three colours falling upon 
the sheet produce white. Some people think of white as 
being devoid of colour; it is clear that white is our whole 
stock of colours blended together. When all our three 
colour sensations are simultaneously stimulated, then we 
see white. 

Now we wanted to make a colour screen which would 
cut off only red rays. What colour must we use for this 
purpose ? It is very easy to find this out, for we have 
red, green, and violet rays all falling upon the lantern 
sheet at present, producing white light. If we close the 
lens from which the red rays are being thrown, we shall 
then have only green and violet rays reaching the sheet. 
Instead of being white, the lantern sheet now appears a 
greenish-blue colour. Therefore, if we make a dye to 
match that colour, we shall be able to make a screen to 
cut off the red rays only. If we have a thin sheet of 
celluloid with a coating or film of gelatine upon it, we 
may dye the gelatine on the screen by dipping it into the 
bath of greenish-blue dye. 

To those who can picture the appearance of the solar 
spectrum with ease, there should be no difficulty in re¬ 
membering that the greenish-blue slide, being a combina- 


ioo 


COLOUR PHOTOGRAPHY 


tion of green and violet rays, will cut off the red rays 
only. In order, however, to make matters perfectly clear, 
we shall not trouble further with the appearance of our 
colour filters, but merely remember that No. 1 screen cuts 
off all the red rays. 

Those readers who have taken the trouble to make a 
book-mark with the colours of the solar spectrum upon 
it, as suggested in the preceding chapter, will find it of 
interest to note below the colour red, minus red = greenish 
blue. 

Our next colour filter is to cut off only green rays. 
We put all three colours on the lantern sheet again, and 
once more we see the sheet to be white. This time we 
cut off the light from the lantern throwing the green 
rays, leaving only red and violet to fall upon the sheet. 
The sheet now appears a crimson pink colour, being a 
combination of red and violet rays. We therefore dye 
our second gelatine film to match this colour. Below the 
green colour on our book-mark we may note, minus 
green = crimson-pink, but we shall only speak of this 
crimson-pink filter as No. 2 screen, being content to know 
that it cuts off green rays only. 

Our third filter is to cut off the violet rays, so we had 
better turn on all the colour lanterns once more and pro¬ 
duce a white sheet. This time we cut off' the violet 
lantern, and we leave only the red and green lanterns to 
light the sheet. The result is a yellow lantern sheet. 
This is quite what we should expect, for if we look at our 
book-mark we find that yellow lies between red and green, 
being an overlapping or blending together of these two 
primaries. Hence the red and green lanterns blending 

IOI 


MORE ABOUT 


their lights together on the lantern sheet produce yellow. 
We must therefore dye our third colour filter to match 
this yellow. We shall simply call this No. 3 screen, re¬ 
membering that it cuts off the violet rays. To complete 
the book-mark, however, it will be of interest to add 
under the violet colour, minus violet = yellow . 

Now we have three screens; No. 1 cuts off' all the red 
rays, No. 2 cuts off all the green rays, and No. 3 cuts off' 
all the violet rays. If we place all three screens together, 
one behind the other, in one lantern, we shall cut off red, 
green, and violet rays, and no light at all will pass out of 
the lantern. Suppose, however, that we scrape away a 
little of the dyed gelatine from No. 1 screen, which is 
cutting off the red rays, we shall then allow red rays to 
pass through at this point. The other two screens cut off 
all the light except the red, so the red light can now 
get out of the lantern through the space we have scraped 
clear. 

Let us deal with red alone first. We can now see how 
it will be possible to reproduce upon the lantern sheet an 
image of the red vase. We take the first, or red, nega¬ 
tive produced by Ives’ process. This negative has an 
opaque image of the vase upon it, so we shall print a 
positive of this on to a sensitised film of gelatine held 
upon a thin sheet of celluloid. When we develop this 
we have a transparent, or clear, image of the vase, and an 
opaque ground on the rest of the plate. In other words, 
we have no gelatine left where the image of the vase is. 
If we now dye this gelatine transparency to match No. 1 
screen, and use it in place of the colour screen, it will 
cut off red light except at that part forming an image of 


102 


COLOUR PHOTOGRAPHY 


the vase. It is just as though we had neatly scraped 
away an image of the red vase upon our original No. 1 
screen, and then placing the other two screens behind this 
one in a lantern, we allow only the red light to pass out 
through the clear image of the vase on No. 1 screen. 

I have spoken of developing the gelatine transparency 
after printing from the negative, but the process adopted 
hardly warrants the title of developing. After the 
sensitised or bichromated gelatine surface of the celluloid 
plate has been exposed to light, under the original nega¬ 
tive, it is only necessary to wash the exposed plate in 
warm water, whereupon the parts which have not been 
affected by light will be washed away. In this case the 
opaque image of the vase upon the original negative 
protected the gelatine, while the remainder of the gela¬ 
tine was affected by light. Hence our resulting trans¬ 
parency or positive would show no gelatine for the image 
of the vase, but a complete ground of gelatine over the 
rest of the plate. 

Let us examine the lantern sheet more closely, and we 
find not only a red vase upon an otherwise dark screen, 
but we also see a red image of the original yellow 
flowers. Suppose we now scrape away a patch of the 
gelatine on No. 2 screen, which is obstructing the green 
rays. We shall at once see a patch of green light upon 
the corresponding part of the lantern sheet. It follows 
that if we dye a transparency made from Ives’ second or 
green negative, and substitute it for No. 2 colour screen, 
we shall cut off all the green rays except at the clear 
image of the leaves. It will be remembered that a clear 
image of the original yellow flowers will also appear upon 
103 


MORE ABOUT 


this transparency; the green rays will not be subtracted 
from the flowers, nor were the red rays, therefore they 
will appear yellow. 

Following up the simple plan of scraping away a patch 
of gelatine film from the colour screens, we find that in 
doing so to No. 3 screen we permit violet light to pass out 
to the lantern sheet from this cleared patch. We there¬ 
fore make a third transparency from Ives’ third or violet 
negative, and we dye it to match our No. 3 dyed screen, 
which cuts off all the violet rays. It will be remembered 
that this third transparency will throw an image of the 
blue figuring upon the vase. This image will be thrown 
in violet light, but as the green transparency will also 
have thrown an image in green of the same figuring, the 
image will now be turned to blue. We now have a com¬ 
plete picture upon the lantern screen : a red vase with 
blue figuring upon it, some green leaves and yellow 
flowers. 

The picture which we have just built up upon the 
lantern sheet is the same as that built up by Ives’ process. 
Wherein then lies the advantage ? It is self-evident. In 
Ives’ process we required three separate lanterns, with 
three separate lantern slides, all to be carefully adjusted 
to exactly overlap upon the screen. In Lumi&re’s and 
Sanger Shepherd’s processes we have only one lantern and 
one lantern slide, which requires no special treatment; 
the slide may be exhibited by any amateur in the ordinary 
way. The three dyed transparencies are mounted together 
between two ordinary plain cover glasses. It is more 
convenient to have one of the dyed films upon glass, and 
then place above this No. 2 celluloid with its dyed film, 
104 


COLOUR PHOTOGRAPHY 


and over that again No. 3 celluloid. These are now bound 
together by placing a plain cover glass over them. The 
two celluloid sheets are very thin, so that the complete 
lantern slide is practically no thicker than an ordinary 
slide. Of course, it is necessary when mounting to see 
that the three pictures exactly overlap, but this is done 
once for all in making up the lantern slide. 

I have purposely taken a very simple illustration for our 
lantern slide, but we have seen how the three primary 
colours and two compound colours (yellow and blue) 
are recorded and reproduced. In the same manner the 
most intricate colourings may be analysed and reblended 
together. 

I have in my hand a lantern slide produced by the 
Sanger Shepherd process. It is a photograph of a large 
basket of different fruits. No artist could produce such 
a natural bloom upon those grapes, nor the infinite variety 
and delicacy of colour in the photograph. I take off the 
plain cover glass of the lantern slide and below this I find 
first of all a yellow film, upon which there appears a faint 
transparent image of some of the fruit and basket. This 
is the No. 3 screen which will cut off the violet rays 
excepting where the screen is left transparent. The most 
opaque object I can pick out upon this plate is a large 
apple, a considerable part of which is dyed yellow. This 
means that practically no violet rays will be allowed to 
pass through this image of the apple. Removing this 
yellow transparency, we next come to the crimson-pink 
film, which is also on a thin sheet of celluloid. Here we 
also find a good deal of the picture as a transparency on 
the crimson-pink ground. Looking at the same apple as 
105 


COLOUR PHOTOGRAPHY 


before, we find its image upon this plate is also fairly 
opaque and is dyed deep crimson-pink. This means that 
practically all the green rays will be cut off from this 
particular apple. 

If we now remove the crimson-pink transparency we 
find a greenish-blue transparency fixed to the under glass 
cover. We see a good deal of the whole picture again as 
a transparency upon this. Picking out the image of the 
particular apple which we have already examined on the 
other transparencies, we find that it is almost quite trans¬ 
parent on this last plate. It has almost none of the 
greenish-blue dye which cuts off red rays. Now placing 
the three coloured transparencies together again, we have 
the first-mentioned one obstructing the violet rays from 
this particular apple, while the second transparency ob¬ 
structs the green rays from the same object, therefore 
leaving only the red rays to pass unobstructed through 
the clear image of the apple on the third transparency. 


106 


CHAPTER VII 


COLOUR PHOTOGRAPHY WITHOUT 
COLOURED SCREENS 

A brief summary—Is colour photography a delusion?—A process 
without coloured screens—Lippmann’s method—Its principle— 
How the colours are produced—Photographing the colours—What 
happens on the photographic plate—Another colourless process of 
reproduction—What is a diffraction grating ?—A demonstration— 
Wood’s process—Early observations—Conclusion. 

C T us now make a brief summary of the three 
different processes of colour photography which 
we have considered up to this point. Ives made a 
separate negative of each primary colour—red, green, and 
violet—thus recording the whole light reflected by the 
objects he photographed. He then made transparencies 
of these three records, and by using three separate 
coloured lights he could reproduce his picture, controlling 
each colour by the record it had made itself. 

Coming next to Professor Joly’s process, we found that 
he took the three primary colour records in consecutive 
lines on one negative. By means of a viewing screen he 
again threw the three primary colours through these 
line records, and thus reproduced the original coloured 
picture. 

In the third process we find Sanger Shepherd reverting 
to the three separate negatives of Ives. He then dyes 
107 


COLOUR PHOTOGRAPHY 


three transparencies of these records. He does not use 
the primary colours for dyes, but obtains three colours, 
each of which will only cut off one set of rays and allow 
the other two primaries to pass through, from the white 
light in the lantern. This, as we have seen, gives us the 
advantage of being able to mount all three coloured 
transparencies together in one lantern slide. 

The reader may consider it a simple delusion to speak 
of any of these processes as being photography in natural 
colours, no matter how beautiful the results may be. Our 
methods have been artificial ; we have used coloured 
screens and coloured dyes. We have certainly done so, 
but only in order to control the coloured rays composing 
the white light. Perhaps this will be more clearly under¬ 
stood if we consider what we really did when we repro¬ 
duced in imagination the simple photograph of the red 
vase with its flowers. How did we reproduce the red 
vase in Sanger Shepherd’s process ? We started with the 
ordinary white light of the lantern, which in passing 
through the yellow filter was robbed of its violet rays, 
and then passing on through the crimson-pink filter it 
was further robbed of its green rays, leaving only the red 
rays to pass through the transparent image of the vase on 
the third filter. We did not dye the vase red; we manipu¬ 
lated the colour rays in white light, subtracting all but 
the red. 

I can see some matter-of-fact reader shaking his head. 
He says it is all very well to talk of colour in that way, 
but there is no getting away from the fact that we have 
used coloured screens. I ask him if he will be satisfied if 
I can show him a photograph in natural colours, which 
108 



By per?nission oj the authorities at New Scotland Yard 

Ten Photographs of Five Criminals 

The photographs in the upper row were all taken some time before those in the lower row. Each pair of photographs is of one criminal. 
It is difficult to realize that the men in the lower row are the same as those immediately above. (See chap, xi.) 























WITHOUT COLOURED SCREENS 


was taken and reproduced without the aid of any coloured 
screens whatever. He is interested at once. 

When the expectant inquirer is shown one of Professor 
Lippmanns beautiful photographs on glass, in which all 
the delicacy of natural colours is seen, he at once con¬ 
cludes that there are coloured screens in this slide also. 
We are not showing him this picture upon a lantern 
screen. We cannot do so ; it must have a reflecting back 
of mercury. If we take the photograph away from the 
mercury back and let him look through the glass photo¬ 
graph, he is convinced that there is no colouring on the 
plate. There is no colouring upon the mercury, which 
merely acts as a good reflecting surface. From whence, 
then, comes all that beautiful wealth of colour when the 
transparent photograph is placed against the mercury 
background ? From the place that all colour comes from 
—out of ordinary white light. This seems very mys¬ 
terious ; but let us watch some child blowing soap- 
bubbles. How do the colours arise ? Why do they keep 
changing P 

When light falls upon the soap-bubble it is reflected 
back, not only by the outside surface of the bubble, but 
by the inner surface of the same wall or film. We have 
nothing to do at present with the other side or wall of the 
soap-bubble; it is only the one very thin film which con¬ 
cerns us. 

When the film or coating of the soap-bubble is of a 
certain thickness it transmits all the red and green rays, 
but reflects back the violet rays. This phenomenon is 
due to the reflection from the inner side of the thin film 
interfering with the reflection from the outer surface. 

109 


COLOUR PHOTOGRAPHY 


We merely observe that as the soap-bubble coating varies 
in thickness, the colours which it reflects also vary. There¬ 
fore if we can make a very thin photographic film on a 
sheet of glass, and if we can arrange that this film can be 
of varied thicknesses, we shall have different colours 
reflected thereby. Light will not only be reflected by the 
surface of the film, but also by the mercury backing, and 
the thickness of the film between its outer surface and the 
mercury reflector will determine the colour which will be 
reflected. 

What I have been briefly describing is really what 
Professor Lippmann has successfully accomplished in his 
process of colour photography. He arranges a thin 
transparent film which is sensitive to light; this he 
places against a mercury background, so that when the 
light enters the camera it not only attacks the surface of 
the film, but is reflected back through the film by the 
bright mercury background, which is in immediate contact 
with the back of the film. The sensitive film is therefore 
being attacked both by waves of light falling directly 
upon it and by waves of light reflected back by the 
mercury surface. There is an interference between these 
two sets of waves of the all-pervading ether. At some 
parts the one set of waves will go to assist the other set, 
and at such places the action upon the chemicals in the 
film will be considerable, so that a comparatively thick 
deposit is made. The deposit will really be in very thin 
layers separated by other thin layers of clear film, accord¬ 
ing, as it were, to the rise and fall of the ether wave 
(light). At other places one wave may go to neutralise 
another, and so on. The actual working of light in the 


i io 


WITHOUT COLOURED SCREENS 


taking of Lippmanns photographs is a much more com¬ 
plex phenomenon than such a simple interference of waves 
as I have just described. Different colours are due to 
different sizes of waves in the ether, so we have not only 
to deal with two sets of simple waves. However, what we 
have to picture, at present, is merely a film so formed 
with varying layers, corresponding to the wave lengths of 
different colours. The existence of these layers in the 
film is not merely theoretical, they can actually be seen 
in the microscope, and photographs of them have been 
taken through the microscope. A colour wave does not 
form only one layer in the film, but a series of layers, the 
distance separating these layers corresponding with the 
length of the wave producing them. 

We now come to consider the reproduction of the 
coloured picture. Although it may seem, at first, in¬ 
credible, it is a fact that when the film, thus formed, is 
developed and dried it will again reflect back all the 
different wave lengths (colours), which produced the 
different layers. It is, of course, not a case of simple 
reflection. The photograph must have its mercury back¬ 
ground to set up a second reflection which will interfere 
with the reflection from the front surface of the film. 
The soap-bubble is a complete analogy; indeed the 
phenomenon in both cases is identical. Some layers will 
reflect to the eye only red waves, other parts green waves 
or perhaps violet waves, but other parts will have layers 
which reflect back both red and green waves together, 
producing the sensation of yellow. In this way every 
variety of colour which affected the sensitive film is 
reproduced. 


COLOUR PHOTOGRAPHY 


Before leaving the Lippmann process, which has only 
been very briefly described, it may be well to remark that 
the photographs taken by this process are usually viewed 
in a dark box with an eyepiece. A strong light is 
reflected into the box to fall at a certain angle upon the 
glass photograph. While this is an improvement it is not 
an absolute necessity. 

There is another process in colour photography which 
requires no colour screens in reproducing its pictures. 
This process was discovered, or I might rather say in¬ 
vented, by Professor Wood, of Wisconsin (U.S.A.). It 
is dependent upon the diffraction of light by means of 
glass plates with lines ruled very close together, two or 
three thousand lines to the inch. This process would not 
be easily understood without going into it at considerable 
length, and would require a series of diagrams. I there¬ 
fore pass it over, only remarking that Professor Wood 
uses colour screens in obtaining his photographs, but he 
reproduces them by means of these finely ruled screens, 
known as diffraction gratings , without the aid of any 
colour screens. Lippmann’s process was entirely free of 
colour screens both in the taking and in the reproducing. 

These two processes are really only of scientific interest. 
One cannot hope to practise such methods with pleasur¬ 
able ease. What the man in the street really wants is a 
direct method of colour photography. He wishes to take 
a simple photograph, develop it, and find all the colours 
already there. 

Many people have maintained that this will be for ever 
impossible. In these days of discovery it is not wise to be 
dogmatic in one’s prophecies. 

112 


WITHOUT COLOURED SCREENS 


Has nothing been done to try and get the different 
colours to fix themselves directly on to a sensitised plate 
or paper ? In connection with the early experiments in 
photography, both Daguerre and Fox Talbot stated that 
sometimes they had found the red objects in a scene to 
impress themselves upon the photographic plates with a 
distinctly red tinge. This would, no doubt, be put down 
to some chance chemical coincidence. Several well-known 
men of science, however, succeeded in getting light, when 
passed through a glass prism, to make a coloured record 
upon a sensitised surface. The resulting spectrum band 
was by no means perfect, but some of the colours were 
fairly good. These colour effects, however, were difficult 
to obtain, and they did not live long; even exposure 
to air seemed as destructive as further exposure to 
light. 

Such experiments were known to scientists more than a 
century ago—quite a generation before photography was 
invented. One might therefore be inclined to say that 
direct colour photography cannot lie along these lines. 
Within recent years, however, particular attention has 
been given to the possibilities of direct colour photo¬ 
graphy, and some interesting progress has been made. 

Some time ago a bleaching-out process was introduced, 
and has recently been improved by Dr. J. H. Smith, of 
Zurich. Through the kindness of a friend I have been 
able to test a piece of this bleaching-out paper. The 
sensitised paper looks as though it had already been 
exposed to light; it is almost black. I first of all placed four 
strips of coloured celluloid alongside of each other—a green, 
a yellow, a blue, and a red. When the paper was exposed 

113 


H 


COLOUR PHOTOGRAPHY 


to light through these colour screens, each colour im¬ 
pressed itself with fair approximation upon the paper. 
That is to say, where green light fell upon the paper it 
turned green, yellow light recorded yellow, and so on. 
The piece of paper with which this experiment was made 
took an exposure of four hours in good daylight. 

The next experiment was to try printing a coloured 
picture. Taking a coloured lantern slide and removing 
the plain cover glass, I made a contact print through the 
lantern slide. The coloured print thus obtained was a 
very fair representation of the original. This again 
required an exposure of four hours in good daylight. Dr. 
Smith has every confidence in making the surface more 
sensitive, so that a much shorter exposure would be suffi¬ 
cient. 

It will be obvious that a glass plate or a film prepared 
in this way and placed in the ordinary camera should 
record the coloured picture falling upon it. A friend 
asked me if I could procure him a piece of the paper, in 
order to try it in the camera. I pointed out that it was 
not sensitive enough for that purpose. What he proposed 
doing, however, was to leave the paper exposed in the 
camera in front of a stained-glass window, and the expo¬ 
sure might be for a week, if necessary. I do not believe 
that any impression could be got in this way. The light 
would be too weak to affect the chemicals, just as was the 
case in the early experiments of Wedgwood and Davy 
with the camera obscura. The chemicals require a certain 
intensity of light to affect them, the intensity depending 
upon the chemical combination. To take a simple 
analogy, we may imagine a glass plate upon which certain 


WITHOUT COLOURED SCREENS 


small objects have been fixed. We arrange matters so 
that a strong blast of air projected upon the surface 
blows these objects away from their anchorage. It is 
quite obvious that we might let a gentle stream of air 
play incessantly upon the same plate without having any 
effect upon the objects. 

This bleaching-out process of colour photography only 
awaits some means of making the surfaces more sensitive, 
and in adjusting the chemicals so that the colours pro¬ 
duced will be as near to nature as it is possible to have 
them. 

I cannot do better than close this subject by again 
repeating the words used by Arago before the French 
Chamber of Peers in 1839 :— 

“The image in its natural and varied colours may 
remain long—perhaps for ever—a thing hidden from 
human sagacity. But let us not rashly circumscribe 
knowledge within impassable bournes. The successful 
efforts of M. Daguerre have disclosed a new order of 
possibilities.” 


CHAPTER VIII 


THE MAKING OF BOOK 
ILLUSTRATIONS 

The first beginnings—Woodcuts and engravings—The meaning of 
etching—Niepce’s early experiments—A failure followed by 
success—Heliography—A surprise reproduction of some diagrams 
—A visit to the block-maker’s—How the blocks are made for the 
printer—A demonstration of Scott Archer’s wet collodion process 
—Zincotype process for line drawings. 

I N order to understand clearly how our present beauti¬ 
ful results in book illustration have been attained, it 
will be of interest to trace the subject, briefly, from its 
earliest beginnings. 

We are not surprised to find that we have to begin in 
China. Indeed, one sometimes feels as though the 
Chinese had discovered everything before the world 
began. The Chinese observed that a block of wood, if 
smeared over with a particular kind of ink, would leave 
a clear impression of itself upon a piece of paper. The 
idea was soon suggested that if they cut away part of the 
surface of the block, and left only the lines of one of their 
language signs, an impression of this sign could be made 
upon paper. The successful printing of these language 
signs led the Chinese to make wooden blocks with figures 
and images upon their surface. 

It is not known exactly when this wood-block engraving 
116 


MAKING OF BOOK ILLUSTRATIONS 


was introduced into Europe, but some museums possess 
prints dating back at least four or five centuries. 

These early woodcuts were merely outlines and spaces; 
there was no attempt at shading. The art of wood¬ 
engraving attained to great perfection in modern times, 
but photographic processes have now stepped far in front, 
and completely revolutionised book illustration. 

In order that we may properly appreciate the part now 
played by photography, it will be well to note briefly how 
hand engravings are made on metal plates. The art of 
engraving upon metal is far older than the art of printing. 
Gold and silver ornaments had for long been embellished 
by engraving designs upon their surface. The goldsmiths 
of Florence increased the decorative effect by filling the 
engraved lines with a black enamel after the design had 
been completed. While at work they had difficulty in 
seeing the part of the design which they had already cut. 
They therefore adopted a plan of inking over the vase or 
ornament occasionally, and then cleaning the surface of 
ink, they pressed a damp paper against the vase, and 
found that they could get a clear impression upon the 
paper of the lines they had already cut on the metal. It 
was a long time before any one suggested this kind of 
engraving as a means of printing pictures. 

It will be observed that engraving upon metal is exactly 
the converse of wood-engraving. In the latter the 
engraver cuts away all the wood except where he desires 
lines to print from, whereas the metal engraver cuts out 
the lines themselves, leaving them as depressions in the 
plate. In the woodcut, therefore, the design stands up 
in relief, and by passing an inked roller across its surface 
ii 7 


THE MAKING OF 


it will receive ink, and that in turn is transferred to the 
paper. All such blocks, on which the lines stand up like 
type, are called relief blocks . Those blocks or plates 
which have the lines sunken below the flat surface are 
called intaglio , and it is obvious that such plates cannot 
be printed from in the same manner as in the relief process. 
If we were to pass an inked roller over an intaglio plate 
we should ink the plain surface and leave the lines of the 
picture without ink. It is therefore necessary to dab on 
the ink so that it may fill up the depressed lines, and then 
clean the plain surface; a process which must be done by 
hand. If a suitable paper be then pressed against the 
engraved plate, by means of a hand-press, the ink will be 
transferred from the lines to the surface of the paper. 
We have photographic processes on both these principles, 
but it will be of assistance to us to note briefly the method 
of etching metal plates. 

The word etching is often used erroneously in connec¬ 
tion with ordinary pen-drawing upon paper. The process 
of etching metal plates consists, first of all, in covering 
the surface of the plates with some composition which 
will resist the action of acids. The desired design or 
picture is made on paper, and transferred by pressure 
to the surface of the composition. The etcher then 
goes over the lines of the transferred drawing with a 
special needle, cutting away the resisting composition 
wherever he finds a line. When this has been done he 
pours some etching fluid or acid over the plate, and the 
acid soon eats its way into the metal wherever the resist¬ 
ing surface has been removed by the etcher. The result 
is a metal plate with the picture sunken into it. This is 
118 























































BOOK ILLUSTRATIONS 


therefore an intaglio process, and the plate must be 
printed from in the same manner as a hand-engraved 
plate. 

It will be obvious that the etched plates required to be 
prepared by some one with artistic talent, or at least 
some one well able to draw. It was our old friend 
Nicephore Niepce who first suggested that the etched 
plate might be automatically produced by the action of 
light. Niepce was very interested in the mechanical 
printing of pictures by means of lithographic machines, 
which had not been long in use at this time (1814). 
Niepce set about trying to make improvements in this 
much-praised invention of Senefelder. One suggestion 
made by Niepce was that metal plates should be used in 
place of blocks of special stone. It was while experi¬ 
menting in this way that the idea occurred to him of 
transferring the lines of the picture to the metal plate by 
means of light itself. Experiments with the salts of 
silver failed to serve any useful purpose. The impres¬ 
sions got could not be fixed. It was then that Niepce 
made experiments with the bitumen of Judea, of which we 
read in the first chapter. 

The bitumen of Judea did not turn black, like the 
silver salts, on exposure to light. What happened to the 
bitumen was something quite different. If it was dis¬ 
solved in certain oils and then spread over a metal plate 
and allowed to dry, it became sensitive to light. The 
action of the light was such that it altered the chemical 
condition of the bitumen. After exposure to light, it 
was found to be no longer soluble in the oils which pre¬ 
viously dissolved it. Here was a way out of Niepce’s 
119 


THE MAKING OF 


difficulty. He now exposed the plate with its bitumen 
surface under the transparent drawing. Wherever the 
light got through to the bitumen those parts became in¬ 
soluble, but wherever the lines of the drawing protected 
the bitumen it still remained soluble. When the exposed 
plate was then placed in the oil bath, the soluble parts, 
corresponding to the lines of the picture, were dissolved 
away, leaving the plate exposed at such places. The 
plate could now be etched by acid in the same manner as 
a plate prepared by the etcher’s needle. No artist but 
Light was required to prepare the etched plate. Niepce 
called this process heliography (sun-drawing), and un¬ 
doubtedly it forms the starting-point for all subsequent 
processes. 

It would only weary the reader to follow out all the 
processes leading up to our present means of reproducing 
drawings or photographs for book illustrations. What 
the reader really wishes to know is, how we are able to 
take a photograph and print it by purely mechanical 
means, like ordinary type. In other words, how can pho¬ 
tography make the blocks for producing such illustrations 
as we have in this present volume. 

Many years ago, in writing some articles for one of our 
scientific journals, I drew out a number of diagrams, upon 
which I scribbled several words opposite different parts, 
thinking that the block-maker or the printer would set 
these in type. I was very much surprised, upon receiving 
the proof-sheets, to find that these ugly scribbles of mine 
appeared in the printed diagrams, exactly as I had 
hurriedly put them upon the original drawings. It was 
quite apparent that the block-maker had simply photo- 


120 


BOOK ILLUSTRATIONS 


graphed the diagrams and put them, by some means, 
directly on to his blocks. Needless to say that in future 
diagrams I took care to carefully print in any words 
required. How then did the block-maker reproduce the 
diagrams on his blocks P 

I think it will be of interest if, in imagination, we pay 
a visit to the block-maker’s. We are fortunate in arriving 
just as the block-maker is preparing to photograph a pen- 
and-ink drawing for reproduction in one of our news¬ 
papers. He has placed the drawing upon an upright 
board, but his camera seems to be pointing in quite a 
wrong direction ; the drawing is at the side of the camera, 
and not facing it. When we go round to the front of the 
camera, however, we find that the lens is turned round at 
right angles, so that it is really facing the drawing. How 
then will the light manage to get round the corner, when 
it enters the camera, in order to reach the photographic 
plate ? After passing through the lens, the light falls 
upon a mirror which reflects it at right angles, so that the 
image of the picture falls upon the sensitised plate at 
the back of the camera. What advantage has been 
gained ? We have certainly not increased our light in any 
way, and yet there must be an advantage of some kind or 
other. Had the image of the picture been thrown 
directly through the lens on to the photographic plate, 
the right hand of the original would have become the left 
hand in the copy. The mirror reverses this, so that the 
picture on the photographic plate is an exact copy of the 
original. 

Some friends remarked to me recently that they had 
been photographed at a country fair, and that until then 


121 


THE MAKING OF 


they had never noticed that in a photograph one’s right 
side became one’s left side. One of the party happened 
to have an injured eye; in the picture it was the opposite 
eye which appeared to be injured. This does not really 
happen in ordinary photography. I have already remarked 
upon this fault in the old daguerreotype process, and it is 
bound to happen in any process in which the photographic 
picture is directly taken in the camera. Our glass nega¬ 
tives are all reversed, but they again reverse the image 
when printing on to the sensitised paper, so that the 
finished photograph is correct. The itinerant photo¬ 
grapher who took the party referred to was doubtless 
making “tin portraits,” which are directly produced in 
the camera; hence the reversal of the image. 

If the block-maker were going to print directly from 
his negatives on to the newspaper, he would have no 
occasion to reverse the image by means of a mirror. But 
he is first of all going to transfer the photograph to a 
block, and on this the image will be reversed. In trans¬ 
ferring the picture from the block to the newspaper the 
image will be corrected again. 

The camera and the pen-and-ink drawing now being in 
position, the operator asks us if we would care to see him 
preparing his photographic plate. He finds it advan¬ 
tageous to use the old wet collodion process of Scott 
Archer, and as this process is practically obsolete for 
ordinary photographic purposes we are most willing to 
witness the preparation of the plate in the dark room. 
The operator takes a sheet of clean glass, and holding 
this in a horizontal position, he pours his collodion mixture 
upon it. He seems to be possessed of some magical 


122 


BOOK ILLUSTRATIONS 


power, for he runs this liquid all over the flat glass plate, 
and yet not a drop runs off* the plate at the edges. Indeed, 
you question if the plate is really flat and not lipped at 
the edges. Your surprise is not lessened when the operator 
tilts up the plate and pours the surplus liquid off* at one 
corner and back into the bottle, leaving an even coating 
upon the glass. It is difficult to realise that it was simply 
a molecular cohesion which prevented the liquid flowing 
over the edges of the plate. The plate is then placed in 
a bath of silver nitrate, whereupon it becomes opaque and 
yellowish white; it is then sensitive to light. The wet 
plate is then placed in the dark slide and is taken out 
to the camera. The pen-and-ink drawing which is to 
have its photograph taken is illuminated by two electric 
arc lamps. The shutter of the dark slide is drawn back 
and the cap of the camera lens removed, giving an ex¬ 
posure of about one minute. 

Another very short visit to the dark room and the plate 
is developed. It has still to pass through several chemical 
baths, after being washed. The purpose of these is to 
build up a stronger image. These processes are carried on 
in daylight, and do not take many minutes. The visitor 
asks why it is necessary to work with the old wet-plate 
process; would not dry plates serve the same purpose ? 
For the block-maker’s purpose the ordinary dry plate is 
too coarse in the graining of its film, and it is difficult to 
make a dry plate that will give as clear a film as is obtained 
in the wet collodion process. The block-maker also finds 
the wet plate an advantage because it is more quickly de¬ 
veloped and fixed. Besides, it only takes him a minute or 
two to prepare his plate; and then he can use the same glass 
123 


THE MAKING OF 


plates over and over again. This is an advantage, as 
sometimes the glass plates are very large. The total cost 
of his chemicals is also very small compared with the price 
of large dry plates. 

While the negative is drying the block-maker prepares 
the v material for his block. As the picture he is repro¬ 
ducing is a pen-and-ink drawing in lines, it will do quite 
well to reproduce it on zinc, the cost of which is small. 
The surface of the zinc plate is polished, and after washing 
it is ready for sensitising. The chemical solution, which 
is already sensitive to light, is poured upon the zinc 
plate. 

The operator has previously fixed the zinc plate to a 
small whirling apparatus, which he holds in his hand. 
The whirling apparatus reminds one of the mechanical 
egg-stirrers with which our mothers 1 cooks used to beat up 
eggs. The purpose of whirling the zinc plate round is 
to throw off the superfluous liquid and leave only a very 
thin film upon the zinc. This film represents old Niepce’s 
bitumen coating. While the whirling operation is being 
carried on the plate is held over a heating stove, so that 
it is dry almost immediately. 

Next comes the transferring of the picture to the sensi¬ 
tised zinc plate. This is done in exactly the same manner 
as one prints an ordinary photograph from a negative; 
the sensitised zinc plate taking the place of the sensitised 
paper. During the printing, the negative and the zinc 
plate must be pressed very close together, and to this end 
the printing frame is made very strong. The block-maker 
finds it more convenient to do most of his printing by 
means of a powerful electric arc lamp. After about three 
124 


BOOK ILLUSTRATIONS 


minutes’ exposure the zinc is ready, but when taken out of 
the frame only a very faint image can be seen. 

Niepce spoke of the image on his plates as being 
invisible, but Daguerre wrote a paper, in 1839, pointing 
out that Niepce was wrong in saying so. One might say 
that in any case the image is very faint, so that there 
seems little to quarrel about, but there is no doubt that 
the point to which Daguerre really wished to draw 
attention was that the image in Niepce’s process was not 
a latent image to be afterwards developed by chemical 
means. Undoubtedly Daguerre was the first to discover 
a latent image, as related in an earlier chapter. 

The block-maker is going to treat his zinc plate very 
much in the same way as Niepce treated his early helio¬ 
graphs, but the operator first of all inks the whole surface 
over with a black greasy ink. He then washes away the 
parts of the film which have not been affected by light 
and which have therefore remained soluble. This leaves 
an image in ink with a support of insoluble chemical 
coating beneath it. The greasy ink is going to act as a 
resister during the etching process, but before placing the 
zinc plate in the etching bath it is necessary to varnish 
the back of the zinc plate to prevent the acid attacking 
it. The face of the plate is now bitten into by the etching 
fluid, except at those parts protected by the inked film. 
This etching process is allowed to go on until the pro¬ 
tected lines of the picture stand up in bold relief. The 
sides of these lines are protected from the acid by dusting 
on a powder and then heating it. 

These zincotypes are just like the old woodcuts. The 
wood engraver drew his picture on a flat block of wood, 
125 


MAKING OF BOOK ILLUSTRATIONS 


and then he cut away some of the wood, leaving the lines 
of the picture standing up in relief above the body of the 
block. In the zincotype we transfer the picture to the 
block by photography, and by means of the etching fluid 
we “ bite away ” the zinc surface, leaving the lines of the 
picture to stand up from the block. The zinc plate is 
then mounted upon a strong block of wood, so that it 
can be properly set in the printing machine, and used 
along with ordinary type. 


126 


CHAPTER IX 


MORE ABOUT BOOK 
ILLUSTRATIONS 

The “ half-tone ” process for reproducing photographs and paintings 
—The great artist Light—Making the negative—The use of the 
process screen—A myriad of photographs in one—Making the 
block—How the screens are made—How the block prints—Other 
beautiful processes—Woodburytype—Photogravure—Collotype— 
How photo-postcards are made. 

I T will be evident that only pen-and-ink drawings can 
be copied by the zincotype process, described in the 
preceding chapter. The picture must be composed of 
lines or black and white patches. One could not copy an 
ordinary photograph, nor a painting, by this method, 
which is essentially a line process. A piece of music is 
easily copied in zincotype, and the cost of making such 
blocks is much less than by the older methods. 

How then can we ever hope to transfer an ordinary 
photograph to a block, so that it may mechanically print 
the photograph on to paper ? Suppose we do sensitise 
a metal plate and then print an ordinary photograph 
upon it from a negative. We shall have the picture upon 
the sensitised metal surface, but we cannot hope to etch or 
“ bite away ” all this complex variety of light and shade; 
we have no distinct lines. The difficulty might seem in¬ 
surmountable, but it has been overcome in a very ingenious 
127 


MORE ABOUT 


way. No doubt the idea was first suggested by some old 
wood-engravings made by the French engravers about the 
middle of the fifteenth century. Instead of merely cutting 
away the wood and leaving lines, these engravers intro¬ 
duced a new effect by cutting so that small upstanding 
dots remained. These raised dots were made of different 
diameters, in proportion to the amount of ink the engraver 
wished to appear upon the paper at any place. This pro¬ 
cess has been called stippling. 

If we could only make a metal plate with a myriad of 
small outstanding dots which could be inked and then 
printed from, we could produce all shades from black to 
white by varying the sizes of the dots. If we made the 
equidistant dots of large diameter so that they almost 
touched each other, they would naturally receive a good 
deal of ink as the roller passed over them, and would 
therefore print a patch of black. If we reduce the size of 
the dots so that we shall have white paper showing 
through between them, the printing will be a mixture 
of black and white, which produces a grey effect. We 
may go on reducing the size of the dots until they are so 
small that the paper looks practically white. 

If we look at a picture made of dots, as in the illustra¬ 
tion on the page opposite, the effect is not very pleasing. 
If one leaves the book open at this illustration and then 
looks at it from the other side of the room, the effect of 
light and shade is really wonderful. The individual dots 
are no longer visible. It would hardly do to make book 
illustrations which required to be viewed in this manner, 
but it is obvious that if we make the dots so small that 
they cannot be seen individually by the eye, the result 
128 



How Photographs are Reproduced in Books 


This photograph has been produced through a very coarse screen in order to show the 
construction. Look at the picture from a distance. (See chap, ix.) 

























































































































































































































































































































































































































































































































































BOOK ILLUSTRATIONS 


will be the same. If the dots are to be so small that one 
cannot see them as dots, how can we ever hope to produce 
them upon metal, and at the same time arrange their 
sizes so that w r e shall have all the variety of light and 
shade ? The great artist Light can do all this for us in 
a few minutes, if we only place the proper apparatus at 
his disposal. No human artist or engraver could manipu¬ 
late such small dots, and yet this great artist Light must 
act on each dot independently. If the reader will take 
a magnifying-glass and examine any of the illustrations in 
this book, he will see that this is no light task to perform, 
as the dots are set so close together that over half a 
million are required to produce one of the larger illus¬ 
trations. 

Are we then to supply the artist Light with a separate 
camera with which to produce each dot ? I see no 
other way of doing it. A statement of this kind will 
seem to be going beyond the scope even of romance, 
and to be across the border-line of sense. The reader 
will remember, however, that the original camera ob- 
scura had no lens; it was simply a hole in the window 
shutter or screen. Then again facing page 316 we have an 
illustration of photographs taken through a pin-hole. 
Suppose now that we arrange a great myriad of pin-holes 
on a single screen, the construction of which we shall 
consider later. At present we shall picture it as a screen 
of fine black gauze or netting supported on a sheet of 
clear glass. We place this screen inside a large camera 
in the position usually occupied by the ground-glass 
focussing screen. We may imagine the image of a picture 
falling upon this gauze screen, just as we find it on the 
i 129 


MORE ABOUT 


ground-glass screen. Asa matter of fact, we should not 
really see an image under such circumstances without the 
aid of a focussing eyepiece, for our screen is clear glass, 
and not semi-transparent like the ground glass. How¬ 
ever, the rays of light to form the image are there, as we 
may prove by examining any part of the screen with a 
suitable magnifying glass, called a focussing eyepiece. 
This eyepiece simply brings the light rays passing 
through the screen to a focus for the eye. We therefore 
picture all the variety of light and shade, of whatever 
subject is in front of the camera, as falling upon this 
glass screen with its myriad of pin-holes. Each pin-hole 
will allow a sharp pencil of light, as it were, to pass 
through it, and it is with those seventy thousand pencils 
that the artist Light is going to make a record upon a 
photographic plate. 

We place a sensitive photographic plate immediately 
behind the pin-hole screen, so that the different pencils 
of light will fall clear of each other. We shall receive 
upon the photographic plate a myriad of separate impres¬ 
sions which, when developed, will appear as tiny dots. 
If the same intensity of light was falling upon all the 
pin-holes, then we should have a plate with dots of 
uniform size. We have, however, a great variety of light 
and shade, so that there will be very energetic pencils of 
light passing through some pin-holes, weaker ones through 
other holes, while there will only be a very faint pencil of 
light through those parts which are in shadow. When 
the plate is developed we shall find that where a strong 
light has come through a pin-hole there will appear a 
comparatively large impression or dot. Where a fainter 
130 


BOOK ILLUSTRATIONS 


light has passed through a pin-hole there will be a corre¬ 
spondingly smaller dot. 

Suppose we wish to make a dotted negative from a 
photograph of a man. We set up the photograph in the 
same position as we had the pen-and-ink drawing in when 
making the negative for the zincotype block. The only 
difference now is that we are going to interpose the gauze 
screen in front of the photographic plate. Without 
going into details, we may picture a strong light being 
reflected from the man’s face, so that energetic pencils of 
light mark the plate at the place where an image of the 
face would fall. We therefore have a series of large dots 
on the negative at this place. The man’s black coat 
reflects very little light, hence small dots will represent 
the image of the coat upon the negative. It is the 
negative we are considering; the dots will be reversed 
when transferred by light to the block. A glance at the 
illustration opposite page 128 shows large dots producing 
the dark objects, and smaller dots the lighter parts. 

The preparing of the wet plate, the taking of the 
negative, and its subsequent development are all identical 
with what has already been described in connection with 
zincotype, with one exception—the introduction of the 
gauze screen. Having obtained our dotted negative, we 
may leave it for a little to consider how the pin-hole or 
gauze screen is made. 

Some of the screens, for fine work, will have four and a 
half million pin-holes in one square foot. How will it be 
possible to make such a myriad of holes so close together P 
The method adopted is very simple. The screen is made 
up of two sheets of glass, each being covered with a series 

131 


MORE ABOUT 


of parallel lines lying diagonally across the glass plate. 
When the two plates are mounted, with their ruled faces 
together, the two sets of lines are at right angles to each 
other, so that they form a gauze or net effect, as 
represented in the accompanying diagrams. 

The method of making the screens is of interest. If 
two hundred parallel lines have to be ruled in one inch, it 
will be apparent that the lines must be very fine. The 
glass is first of all given a chemical surface, or film, which 



will resist the action of an etching fluid. The necessary lines 
are then cut into this chemical composition by means of 
a dividing machine, thus laying the glass bare along these 
lines. When the prepared glass plate is now put into a 
special etching bath containing fluoric acid, the fluid eats 
into the glass along these exposed lines. The result is a 
series of very fine grooves in the glass. These are then 
filled in with a black enamel, thus producing a screen 
covered with very fine parallel lines in black. 

A second screen is made identical with the first one, the 
lines running in the same direction. Then when this 
second plate is turned face downwards upon the top of the 
132 







BOOK ILLUSTRATIONS 


first, the two sets of lines will cross each other and form 
the network of small holes. It will be apparent that, in 
the accompanying diagram, No. 1 is shown face upwards, 
but No. 2 with its ruled face downwards, ready to place 
on the top of No. 1. 

A very coarse screen, say for poster work, may have 
only fourteen lines to the inch. The illustration opposite 
page 128 has been taken through a sixteen line screen, 
whereas the majority of the illustrations have been made 
through screens having 175 lines to the linear inch. 

Having already prepared his dotted negative, the block- 
maker proceeds to make a block for the printer. He takes 
a plate of copper this time instead of zinc, because it is 
more durable and gives a more perfect and a harder sur¬ 
face. The surface of the copper is sensitised and then a 
photographic print made upon it, through the dotted 
negative. The copper plate is then washed to remove 
those parts of the film which have been unaffected by 
light. The plate is then baked at a high temperature in 
order to harden the film. It is next placed in the etching 
bath. The surface of the copper plate is bitten away, 
leaving only a myriad of small dots of varying diameters. 
This biting away is continued until the small dots repre¬ 
senting white in the picture have almost disappeared. 
After the plate is well washed it is mounted upon a block 
of wood and made ready for the printer, who may print 
with it in his high-speed machines just as though it 
were ordinary type. 

It is, indeed, remarkable that when this seemingly 
smooth block is inked by passing under a roller in the 
ordinary way, each separate tiny dot is able to transfer an 
133 


MORE ABOUT 


image of itself in ink on to the paper. The dots are all 
very small and very close together, giving the appearance 
of a perfectly smooth surface, so that one would not be 
surprised if only a very smudged effect were the result of 
printing. Each illustration in this book is a witness to 
the fine work performed by those little dots. When we 
consider that these tiny dots are practically invisible to 
the unaided vision, is it not wonderful that they can act 
like type and print thousands of copies of those beautiful 
photographs ? 

It is interesting to note that the block-maker can vary 
the shape of the small dots upon the negative, which in 
turn determines the formation of the dots upon the metal 
block. We may picture each space in the ruled screen as 
acting like a pin-hole camera and giving an image of the 
aperture of the lens of the large camera. The operator 
may therefore insert diaphragms, with differently shaped 
openings, in front of the lens. If he uses a diaphragm 
with a square opening, then the little dots will all be 
square, and so on. 

In the earlier part of this chapter we saw how line 
drawings are transferred to the printer’s block by means 
of photography; the process being called zincotype. 
Then we have just been considering how paintings or 
actual photographs may be reproduced by means of pro¬ 
cess screens. This process is descriptively named the 
half-tone process. I have gone into the particulars of 
these at considerable length, because they are the two 
processes most commonly in use at the present time. The 
one great advantage, in these processes, is that the print¬ 
ing surface stands up in relief, so that the zincotype and 
134 


BOOK ILLUSTRATIONS 


the half-tone blocks may be used along with ordinary 
printing type. The rate of production in printing is 
therefore very great, and the cost correspondingly small. 

We have already noted that when a printing surface is 
not in relief, but has its lines sunk below the surface of 
the plate, as in the copper plates engraved by hand and 
in the early heliography of Niepce, the process is known 
as intaglio. This is an Italian word meaning to carve or 
cut. It will only be possible to give a very brief descrip¬ 
tion of a few well-known intaglio processes. It will be well 
to include this description, for if the inquiring reader 
examines illustrations in different books with the aid of 
a magnifying glass, he may be puzzled when he comes 
across an illustration which it is clear is neither a zinco- 
type line block production nor a dotted half-tone. 

The most perfect of intaglio processes is one known as 
woodburytype, being so called after its inventor. Here 
we have the original idea of Niepce appearing again. A 
preparation of bichromated gelatine takes the place of 
Niepce’s bitumen. This prepared photographic plate is 
exposed to light under a negative, and the gelatine is then 
dissolved away, its solubility being in proportion to the 
amount of protection offered it by the negative. A mould 
is therefore formed in the gelatine, the deepest parts being 
under the dark portions of the negative, and the shallow¬ 
est parts being under the most transparent portions of the 
negative. Now comes a most remarkable part of the pro¬ 
cess. If this gelatine mould be placed in a hydraulic 
press, with a sheet of lead over it, and an immense press¬ 
ure equal to about four tons to the square inch be applied, 
i35 


MORE ABOUT 


a clear impression is left in the lead. This lead mould 

is, of course, a reverse of the gelatine mould; the pro¬ 
jecting gelatine is now represented by a depression in the 
lead mould, and the sunken portions of the gelatine stand 
up in relief upon the lead. Let us trace the process by 
looking at a white object in the original picture which is 
being copied. The white object appears as a black patch 
upon the photographic negative. This opaque patch pro¬ 
tects the gelatine when it is exposed to light, so that, on 
being washed, the gelatine at this part will be dissolved 
and there will be a consequent depression. The hydraulic 
press will force the lead into this depression, producing 
the same formation in relief upon the lead; this now 
represents the white object in the original picture. 

From what has been said, it will be clear that the 
variation of light and shade in the original picture is 
represented by variations in depth of mould in the lead. 
If a warm gelatinous ink be now poured into the lead 
mould and a well-sized paper be firmly pressed down upon 

it, the paper will lift out the whole of the ink. The ink 
will be thickest at the greatest depressions and least at 
the shallowest parts. In this way a beautiful copy of 
the original picture is reproduced with very perfect grada¬ 
tion of tone. It will be quite evident, however, that this 
process must be a very slow one compared with the half¬ 
tone process, which is printed like ordinary type. 

We have seen, in this woodburytype process, that a 
gelatine mould is able to impress all its variations of 
depth upon a sheet of lead. It is very surprising to learn 
that after this gelatine mould has been subjected to an 
immense pressure, which would be equivalent to about 
136 


BOOK ILLUSTRATIONS 


one hundred tons for an illustration to suit this page, the 
gelatine mould remains uninjured and ready to produce 
further lead reverses if desired. 

Another important intaglio process is that known as 
photogravure , which reproduces the shades of the original 
with great artistic effect. I saw some illustrations being 
made recently, by this process, for a book on birds. It 
was really very difficult to detect any difference between 
the artist’s black-and-white drawing and the printer’s 
photogravure. One could have believed that every copy 
had been specially drawn by the artist. How is this 
interesting feat accomplished ? 

First of all the photographer photographs the artist’s 
drawing. From the resulting negative a positive is taken 
on a surface of bichromated gelatine, or as it is more 
commonly called, a carbon tissue. When this exposed 
carbon tissue has been washed, there remains a mould of 
varying depths, as described in the preceding process. 
This gelatine film is floated off its support and trans¬ 
ferred to a copper plate, which has been previously treated 
with bitumen dust to give it a grained surface. The 
gelatine film is transferred to the copper plate before 
being washed. The plate is next placed in a bath of 
etching fluid, which can make its way through the gelatine 
and attack the metal plate. It naturally gets through 
the thinnest parts of the gelatine first, and bites in to 
some depth at such places before it has reached the plate 
through the more dense parts of the gelatine. The action 
is allowed to go on until the fluid just commences to act 
on the places under the thickest gelatine. The copper 
i37 


MORE ABOUT 


plate has now been etched, and the result is a very much 
more perfect representation of the different tones of light 
and shade than the most expert hand engraver could 
produce. 

The engraved or etched plate • is then given a thin 
electro-plating of iron to produce a harder surface than 
the copper. It is now ready for the printer, who inks the 
plate all over by hand, and then cleans the ink away from 
the surface, leaving the sunken image filled with ink. 
When a suitable paper is pressed firmly down upon the 
plate, by means of a hand-press, the ink is transferred 
from the depressions to the paper. The result is a 
beautiful picture very closely resembling the artist’s 
original drawing. The production of photogravures is 
necessarily slow and costly, the inking of the plate and 
the printing requiring to be done by hand. Recently a 
process of printing photogravures by machine has been 
invented, but is not in general use. 

Another interesting process belonging to the same class, 
but depending upon a different principle of printing, is 
called collotype. The bichromated gelatine is exposed 
and treated in the usual way. The parts which have been 
exposed to light will not only become insoluble, but by a 
special treatment the surface is divided up into a grain— 
a process known as reticulation. This will vary in pro¬ 
portion to the amount of change produced by exposure to 
light under the negative. If we now pass a roller with 
greasy ink over the plate, we shall find that the grained 
surface will print the different tones. In this way the 
collotype block can transfer the required amounts of ink 
138 


BOOK ILLUSTRATIONS 


to paper and produce a picture very closely resembling 
the original photograph. 

Photography has been applied to the production of 
illustrations in many other ways, but I fear further details 
might become wearisome. The processes we have already 
considered are those in most common use. I think it 
will be of more general interest if we now inquire how 
photography has enabled us to produce those beautifully 
coloured pictures by what is known as the three-colour 
process. 

Before closing this chapter it may be of interest to con¬ 
sider the making of photographic post cards. 

The present is the day of pictorial post cards. The 
handling of these alone by the Post Office is a great 
undertaking. There were hundreds of millions of these 
sent through the post last year; probably not less than 
one million per day. 

Pictorial post cards are not all made by photographic 
processes, but a very large proportion are, either directly 
or indirectly. Surprisingly large quantities are actual 
photographs printed directly on to sensitised post cards. 
This is not merely a hobby with amateur photographers, 
but is also done on a large scale commercially. Small 
machines are made whereby the printing of these may be 
carried out very expeditiously. 

There are many cases of amateur photographers paying 
their holiday expenses by making picture post cards of 
local interest. A direct photographic post card will sell 
retail at threepence, and if the amateur gets twopence 
from the shopkeeper, then rather more than half of his 
139 


MORE ABOUT 


takings will be clear profit. But what about the time 
required to produce the cards by hand P A simple calcu¬ 
lation on the foregoing basis shows that the amateur 
must turn out over two thousand cards to earn ten 
pounds. Imagine printing two thousand photographs ! 
It does seem a serious undertaking, and yet amateurs 
have accomplished this. Specially rapid bromide post 
cards are made, which require only an exposure of one 
second to the light of an incandescent gaslight. The 
latent image is developed afterwards. 

Here is a note given by one authority of the time 
required to produce fifty post cards. With suitable 
apparatus the printing will occupy ten minutes, de¬ 
veloping and fixing twenty minutes, “squeegeeing’ 1 fifteen 
minutes, which makes in all about forty-five minutes. 
The prints have to be washed for about an hour, but as 
that process is automatic it need not be included. If 
handling a batch of one hundred post cards at one time, 
they may be completed within an hour. If this rate of 
production could be kept up, the amateur photographer 
would be earning over eight shillings per hour. He would 
probably require to turn professional to find an outlet for 
his productions. 

All the direct photographic post cards, however, have 
not been printed and developed by hand. One company 
possesses an automatic machine which can print and finish 
real photographs “ by the mile.” The actual working of 
the machine is a trade secret, but its general principle 
may be described here. A large roll of sensitised bromide 
paper, wide enough to take in many photographs across 
it, is placed in a large machine. At one part of the 
140 


BOOK ILLUSTRATIONS 


machine a number of photographic negatives are firmly 
fixed in a strong frame. The machine feeds the paper 
forward, then presses one portion against the negatives, 
while a short exposure is made to artificial light. The 
machine then carries the paper forward to the develop¬ 
ing and fixing baths, and finally passes out the finished 
photographs. The whole processes are continuous and 
automatic. 

A large quantity of picture post cards arc made by 
the half-tone and by the collotype processes. 


CHAPTER X 


THE THREE-COLOUR PROCESS OF 
PRINTING 

Taking the negative—Making the block—Mixing of coloured pig¬ 
ments—We do not make colours—What the artist does—Why his 
fundamental colours are not the same as the primary colours— 
Addition and subtraction—An experiment in colour subtraction— 
A simple illustration—A convincing experiment—How the artist’s 
fundamental colours are determined—An unnecessary confusion 
—The printer’s inks — Another lantern demonstration—Three- 
colour printing dependent upon photography—Printing the picture 
—A simple case—The effect of each block—Entirely subtraction 
—Achievement of the artist Light—Some interesting points about 
the blocks—Ideal colour photography—What is the four-colour 
process ? 

C OLOURED pictures have been made by the litho¬ 
graphic press or machine for quite a long time 
now. Each colour appearing in the picture 
requires a separate stone or block. One stone carries 
those parts of the picture which are to be printed in red, 
another those parts which are to be green, and so on. 
Each colour has its separate stone with its particular part 
of the picture. By this means a coloured picture is 
patched together by lithography. 

When it became possible to transfer photographs to 
blocks by means of the process screen, as described in the 
preceding chapter, there was a natural desire to repro¬ 
duce photographs in colours. If we think of all the 


42 


THREE-COLOUR PROCESS 


different processes of colour photography with which we 
have already dealt, we have no hesitation in selecting the 
Sanger Shepherd process as a possible solution of the 
printing problem. It will be remembered that three 
separate negatives were taken in this process. One of all 
the red rays, another of all the green rays, and a third of 
all the violet rays, thus recording all the colours in the 
objects being photographed. A lantern slide was pro¬ 
duced by making three positives or transparencies from 
these negatives, and then dyeing each transparency a par¬ 
ticular colour, and placing one on the top of the other. 

Suppose we now take the three separate negatives, and 
instead of making the transparencies, we make three 
separate half-tone blocks, one from each negative. The 
ordinary negatives will not serve our purpose; we must 
take them through the process screen in order to get the 
little dots, which will stand out in relief upon the print¬ 
ing plate. It will be obvious that there are two ways of 
obtaining the desired negative. 

Suppose we are going to reproduce a water-colour 
painting. We may, Srst of all, photograph it through a 
red glass, and at the same time we may insert the process 
screen in the camera, so that the negative representing 
the red in the picture will appear in little dots. We may 
then do the same for the green and the violet negatives. 
Another way of securing the dotted negatives is to take 
ordinary negatives through the colour filters, and print 
positives of these in the usual way. Then each of these 
positive prints has to be photographed again through the 
process screen in order to obtain the dotted negatives. 

Having obtained the three dotted negatives, which 
M3 


THE THREE-COLOUR 


together represent all the colour in the picture, we pro¬ 
ceed to make a separate half-tone block of each. If we 
examine these three blocks, we shall find that they are 
quite different from simple colour blocks, on which one 
part of the picture appears on one block, and another 
part on another block. Here we have a continual over¬ 
lapping ; indeed, each block seems to include almost the 
whole picture in some degree. A brown object is clearly 
seen on all three blocks. It will be obvious that we in¬ 
tend printing one colour on the top of the other. 

From what has been said already in connection with 
colour photography, it will be clear that we do not pro¬ 
pose to print from these blocks in the three primary 
colours—red, green, and violet. We remember that the 
mixing of coloured pigments is not the same as the 
blending of coloured lights. The former is a case of 
subtracting colours from white light, whereas the latter 
is a simple case of adding coloured lights together. 

Before attempting to print a picture from these three 
blocks, it will be well worth our while to consider the 
mixing of coloured pigments, dyes, or inks. There is 
often some difficulty in clearly understanding the differ¬ 
ence between the mixing of pigments and the blending 
of coloured lights. A purely scientific explanation is of 
little assistance to the general reader, and I have no hesi¬ 
tation in asserting that the difficulty does not exist in 
the minds of unscientific people alone. There seems to 
me to be only one way in which the general reader may 
easily grasp the subject and thereby dispel all confusion. 
He must expel from his mind altogether the idea that in 
mixing pigments, dyes, or inks, he is making colours . 

144 


PROCESS OF PRINTING 


Our whole stock of colours lies around us in white light. 
All we can do is to sort out the different coloured rays 
contained in white light; every colour that has at any 
time been produced has simply been a manipulation 
of light. That is where the artist got all his colours. 
Some one may object to this statement, and say that the 
artist really procures all his colours from the artist’s 
colourmen. He undoubtedly purchases his paints there, 
but these are merely pigments with which he can manipulate 
the colours which are already blended together in the white 
light falling upon his canvas. If an artist friend disputes 
the point, we ask him to look at his paint-box by the 
light of a mercury vapour lamp, or if that is not con¬ 
venient we make up a sodium light by mixing some 
ordinary salt in methylated spirits, as we did in an 
earlier chapter. We then ask the artist where his red 
paints have gone. These paints are now colourless, and 
yet their chemical or physical condition has not changed. 
There is no red colour simply because there are no red 
rays in the light which is falling upon the pigments. 
Perhaps I have pressed this matter far enough, but I am 
anxious that it should be perfectly clear that the mixing 
of so-called colour pigments is merely a manipulation of 
ordinary light. 

Some one may say at this point that he sees quite 
clearly that the pigments are merely absorbing certain 
colour rays and reflecting others, but he cannot see why 
red, green, and violet should not be the primaries when 
dealing with pigments just as with coloured rays of light. 
Surely he has forgotten for the moment that the mixing 
of the pigments is merely the manipulation of the colour 
k 145 


THE THREE-COLOUR 


rays already existing around him. Certainly there are 
only three primary colours, and these are red, green, and 
violet. The artist may have three fundamental or 
primary pigments, but that is quite another matter; he is 
only going to use these for manipulating the three primary 
colours contained in white light. 

Why should red, green, and violet paints not give the 
same result as is got by blending three lights of these 
colours together ? The matter is really very simple. Let 
us take a piece of white paper; there on the paper we 
already have the whole stock of our colours reflected in 
white light. Some reader may consider that the colours 
are only there “ theoretically.” We assert that the 
colours are there in reality. We let a beam of light fall 
upon the paper, passing through a glass prism on its 
way. We at once see all the colours of the rainbow. 
We point out the three primaries—red, green, and violet— 
remembering that the other colour effects may be produced 
by different combinations of these three colours. If we 
withdraw the prism we see no colour, but the colours 
must still be there. It is only when our three colour 
sensations are simultaneously stimulated that we see 
white. We are bound to admit that the colours are really 
there upon the white paper. 

Suppose we cover the white paper with a red paint, 
what have we really done ? We have applied some sub¬ 
stance which has absorbed, or blotted out, all the green 
and violet rays of the white light, leaving only the red 
rays to be reflected to our eyes. We have nothing left 
on the paper but the red rays. There we say we have 
our first primary colour, and we are going to attempt to 
146 



RICHARD CdiUK DE l.ION AND HIS FLEET 
OX THE WAY TO T HE Hoi.Y LAND. 


'Phe Thrke-Coi.oitr Process of Printino. 

The above shows the three separate printings which w hen printed one on the top of 
the other produce the complete picture. The blocks are prepared by photography, 
as explained in Chapter X. The above illustration has been taken from /he L ntsaders , 

by Professor Alfred J. Church. 




































PROCESS OF PRINTING 


combine red, green, and violet to produce white, just as 
Ives did in his triple-lantern process. We next take 
some green paint, or transparent dye, with which we can 
overlap the red on the paper. We know that this green 
dye will cut off the red and the violet rays, but our paper 
is at present only reflecting red rays, so that a transparent 
coating of green will cut off these red rays, and we shall 
have no rays at all reflected from the paper; it will 
therefore appear black. 

It is now quite clear that the mixing of coloured pig¬ 
ments is different from the blending of coloured lights, 
but some reader might still like to ask why there is a 
difference. I think there can be no simpler definition 
than that already given; the blending of coloured lights 
is a case of addition , whereas the mixing of colour pig¬ 
ments or dyes is a case of subtraction . The artist often 
wishes he could add light as he puts his coloured pig¬ 
ments upon the canvas. 

Take as an illustration of the first case Ives 1 three 
lanterns independently throwing red, green, and violet 
lights upon the lantern sheet, so that they fall one on the 
top of the other. Suppose we have the three lanterns 
all ready with their respective colour screens or filters in 
position, but we have a shutter over each lens. Ives 
therefore starts with no colour—darkness—on his lantern 
sheet. He first opens the one lens and throws red upon 
the screen ; he then adds green to this, and the two lights 
overlapping or blending together produce the sensation 
of yellow. He then adds violet light on the top of the 
red and green, when all three together produce the effect 
of white. Our whole three sensations are simultaneously 


i47 


THE THREE-COLOUR 


excited. This has been a clear case of addition; we 
started with a blank sheet—darkness—and we added the 
three primary colours together. \ 

In the second case, the mixing of coloured pigments, 
we set off with all three colours—white light—reflected 
from a piece of paper. We apply a red dye, and thereby 
we blot out the green and violet rays, leaving only red. 
That is quite a big subtraction already. We then add 
a green dye, which absorbs the remaining red rays, and we 
have nothing left. It is a clear case of subtraction. 

In describing his process of colour photography Sanger 
Shepherd has said that his method is one of subtraction. 
This has no doubt been said in order to differentiate it 
from Ives’ process. But is not all colour manipulation a 
case of subtraction P I believe that any other way of 
looking at the matter is sure to lead to confusion. We 
can only have an addition where we have separate indi¬ 
vidual lights, such as in Ives’ triple-lantern process. As 
long as we are painting or printing on white paper or 
other substances, we are merely manipulating the colours 
already contained in white light, and our manipulation 
must necessarily be one of subtraction. 

Let us take a very simple illustration. We have a 
new wooden door, and we send for the house painter to 
come and paint it red. The painter does not really bring 
the red colour with him; the colour is already there, 
reflected from the door in white light, before we ever sent 
for the man. The door is reflecting red, green, and violet 
rays blended together, and producing the sensation of 
white. What the painter really does is to apply a sub¬ 
stance which will absorb or subtract all the green and 
148 


PROCESS OF PRINTING 


violet rays, leaving only the red rays to excite our vision. 
Some one may suggest that we are taking a very round¬ 
about way of thinking; he would prefer to speak of 
simple addition. Why, you can see the red stuff* in the 
painter’s pail, and you see the painter add that to the 
door. Certainly we see the “red stuff” in the pail, 
because the property of that substance is to absorb the 
green and violet rays of light, and reflect only the re¬ 
maining red rays. But we are forgetting again that the 
red colour is not an inherent property of the substance in 
the pail. But as the painter only exists in imagination, 
we can afford to detain him without fear of running up a 
big wages bill. 

We take the painter indoors. We close the window- 
shutters and light the gas or turn on the electric light. 
We ask him to look at the red stuff in the pail; it looks 
very much the same as before. We then prepare a 
sodium light, as we have done on two previous occasions, 
by mixing salt and methylated spirits together. As soon 
as we have set a light to this mixture we turn off the gas 
or electric light, whereupon the red stuff' in the pail is no 
longer red. This particular painter happens to be rather 
a duffer, and he blames me for spoiling his pot of good 
paint. I relieve his distress by extinguishing the sodium 
light and turning on the gas or electric light, or by 
opening the window-shutters. He once more sees his 
paint red, and he is quite satisfied that no chemical or 
physical change took place in the paint-pot. I fear he 
goes away only mystified and not enlightened. 

I tell an artist friend that, before he ever puts a brush 
to his canvas, all the colours he is going to have are 
149 


THE THREE-COLOUR 


already there upon the canvas. I fear that, unless he has 
a scientific mind, he will think I am merely making fun, 
or that I require a mental rest. It is none the less true; 
the artist merely mixes his pigments together, and thereby 
subtracts the green and violet rays from one part of the 
canvas, leaving the red rays to be reflected to the eye, and 
so on. 

It is clear that the artist’s fundamental colours must 
be different from the three primaries with which we have 
been dealing, but how are these colours determined by 
the artist? The artist has long known that if he has 
what are usually called red, yellow, and blue paints, he 
can mix these together and produce practically any 
desired colour and shade. Indeed, it is common practice 
for the artist and the colourman to call these the three 
primary colours. Hence arises considerable confusion. 
It is quite right that they should call these their three 
fundamental or primary paints, but I most emphatically 
protest against the practice of calling these the three 
primary colours. There are but three primary colours— 
red, green, and violet. The primary red pigment is not 
the same as the red of the spectrum, and the same applies 
to the printer’s ink. 

The printer’s three inks should really be the yellow, 
greenish blue, and crimson-pink, as used in colour pho¬ 
tography (Sanger Shepherd process), but in practice they 
differ considerably, so that we shall merely call them 
yellow, blue, and red inks. The red ink does not only 
reflect the red rays of light; it also reflects the violet 
rays of light, causing these two colour sensations to be 
excited. Our primary red colour, on the other hand, 
150 


PROCESS OF PRINTING 


affects the red sensation only. In the same way the 
printer’s blue ink reflects both the green and the violet 
rays of light, while our primary violet colour affects only 
the violet sensation. Therein lies the whole difference, 
and it cannot be said that it is merely a theoretical 
difference. 

The printer’s third fundamental or primary dye is 
yellow. This dye or ink reflects both red and green rays 
of light, and the simultaneous excitement of these 
two sensations produces the effect which we recognise as 
yellow. 

The artist and the printer know that these three 
primary paints or dyes will enable them to produce prac¬ 
tically every colour, but what is the reason underlying 
this fact ? Think again of the white sheet of paper. 
There we have every colour we can ever possess. The 
colours are blended together to form white light. Now 
in order that we may manipulate this combination of red, 
green, and violet rays to full advantage, we must be able 
to subtract each colour separately at will. Red paint, 
corresponding with the red of the solar spectrum, sub¬ 
tracts both the green and the violet rays, leaving only 
the red rays to affect our vision. What we want is a 
pigment or dye which will subtract only one, and leave 
the other two primaries intact. The experiments which 
we made in order to help us to understand the Sanger 
Shepherd process of colour photography will be of service 
again. 

We take three separate lanterns, and by placing a red 
glass screen in one lantern, a green screen in the second, and 
a violet screen in the third, we cause these three coloured 


5i 


THE THREE-COLOUR 


lights to fall one upon the other on the lantern sheet. 
The sheet appears white, or at least practically so, for it 
is difficult to get our colours of exactly the right hue. Let 
us now subtract one of these primary colours. Suppose we 
cut off the light from the violet lantern, and leave only 
red and green to overlap upon the sheet, we shall then 
see the sheet yellow. A yellow ink will therefore subtract 
only the violet rays from white light. If he prints yellow 
ink on to a paper, he merely subtracts the violet rays of 
light. 

We then set all three lanterns once more, whereupon 
we see the sheet white. This time we cut off the green 
light, and there we have a crimson-pink sheet. A crimson- 
pink or red ink therefore subtracts the green rays. Once 
more all lanterns alight, and we have a white sheet. On 
this occasion we shut off the red light, thus causing the 
sheet to appear a greenish blue. Greenish blue or blue 
ink therefore subtracts the red rays. 

We shall stick rigidly to the idea of subtraction. To 
sum up: yellow ink subtracts violet, the red ink subtracts 
green, and the blue ink subtracts red. Some readers may 
think that I have forgotten that my subject is photo¬ 
graphy, I have written at so great a length upon the 
subject of colour, but I see no other way of explaining 
the three-colour process. If we did not first of all fully 
grasp the meaning of colour, we could only form a very 
imperfect notion of the three-colour process. 

This interesting process of printing coloured illustra¬ 
tions is dependent upon photography. It is by means of 
the camera that we can make the necessary printing 
blocks. As we have dealt with the making of the three 
152 


PROCESS OF PRINTING 


blocks in the early part of this chapter, it only remains 
for us to see how the colours are reproduced on paper. 
Let us take the very simplest illustration : a violet flower 
and green leaves in a red vase, the background being 
black. 

The printer finds it necessary to print his yellow ink 
first, as it is not so transparent as the others. Then he 
prints his red ink on the top of that, and finally his blue 
ink on the top of these two. 

It will be remembered that we have already prepared 
a block to subtract violet from every part of the picture 
except where it is wanted. We only wish violet in the 
flower, and so we print yellow (which subtracts violet) over 
the whole paper except for the flower. 

If the reader turns to the coloured illustration facing 
page 154, he will see a simple demonstration of three- 
colour work such as I am describing. 

We start with our whole stock of colour on the plain 
white paper. This first block (yellow) subtracts violet 
rays, the second block (red) subtracts green rays, and the 
third block (blue) subtracts red rays. Therefore, where- 
ever the three blocks print, one on the top of the other, 
we subtract red, green, and violet, which is our whole 
stock. Hence we leave the background in our illustration 
without any colour (black). 

Our first block leaves the flower in white, which means 
red, green, and violet, but the other two blocks subtract 
the green and the red respectively, and therefore leave 
only violet to be reflected, as is seen in the complete 
picture at Fig. B. 

The leaves are left white by the second block, but the 
i53 


THE THREE-COLOUR 


other two blocks rob them of violet and red rays, leaving 
only green rays, as seen in the complete picture. 

The vase is left white by the third block, but the other 
two blocks rob the vase of violet and green rays, so that 
red alone is left to be reflected. 

Our picture is complete—a red vase, green leaves, and 
a violet flower—but what a very roundabout way of pro¬ 
ducing it! Why not simply print the vase red, the leaves 
green, and the flower violet ? It must be understood that 
this picture is merely explanatory ; no picture is so ideally 
simple as to contain only objects of the three primary 
colours. From Fig. C it will be seen how the three 
printing inks overlap and produce those colours, making 
in all six colours and black. But this is not all, for the 
half-tone blocks can vary the proportion of each colour 
and thus produce endless variety of shade. 

It will be remembered that the block made from the 
photograph taken through the red screen does not merely 
record red objects, but also the red rays contained in any 
other compound colour, and so on. The infinitely com¬ 
plex variety of colour is first of all analysed into the 
three primaries. We then make these three records sub¬ 
tract the three primaries from white light in the required 
proportions to reproduce the original picture. The 
records could not be made by the hand of man; it is 
only the great artist Light who can satisfactorily make 
these records by photography. 

The printer has to take great care that his second print¬ 
ing exactly overlaps the first, and so on. If there is any im¬ 
perfect overlapping of the blocks, the picture is imperfect. 

There is another point of interest about the dotted 
i54 




Simple Demonstration of Three-Colour Printing. 


S4‘0‘ fHI <J<‘ /.)•?. 












PROCESS OF PRINTING 


blocks. If two pieces of fine muslin or net are laid one 
upon the top of the other there is produced a moire 
effect, such as is seen on “ watered silks.” The experi¬ 
ment is worth trying. If one of the pieces of muslin is 
turned round so that its threads are at an angle to those 
of the other piece, this moire effect disappears. If the 
block-maker took his three negatives through screens with 
the lines all lying in one direction he would be troubled 
with this moird effect when one block is printed on the 
top of another. He therefore uses different screens, on 
which the series of lines are at different angles to each 
other. If one takes a magnifying glass and examines the 
dots on the three-colour picture opposite page 146, one 
will see the lines of dots of each block have been at 
different angles. 

The majority of illustrations made by the three- 
colour process are reproductions of paintings, but many 
beautiful illustrations of still life have been made direct 
from nature. The three-colour process of printing is 
really the nearest approach to natural - colour photo¬ 
graphy. If our colour screens or filters for taking the 
three negatives were absolutely pure spectrum colours; 
and if our photographic plates could record and reproduce 
the exact proportions of the different coloured rays; and 
if each printing ink could perfectly subtract its own 
primary colour and nothing else: then we should have a 
natural-colour photography. But we have three “ ifs ” in 
the preceding sentence, and doubtless a few more might 
be added. It reminds one of the old nursery rhyme :— 

If ifs and ans were pots and pans, 

There’d be plenty of work for the tinker’s hands. 

155 


THREE-COLOUR PROCESS 


The photographer, the block-maker, and the manufac¬ 
turer of printer’s inks are already doing good work, and 
without a doubt they will advance still further. 

Think of the advance already made by the three- 
colour process. In ordinary lithographic printing, some¬ 
times the printer has occasion to use as many as twenty 
different stones or blocks in order to build up his coloured 
picture. Photography enables us to get every variety of 
colour from three blocks, and the results stand head and 
shoulders above the older methods. 

What about the four-colour processes? The fourth 
block is usually printed in a neutral colour, or in black, 
and is merely to add depth to the picture, or to try and 
neutralise some of the shortcomings in the combination of 
the other blocks. As far as we are concerned this is a 
technical detail, so that the subject does not interest us. 
Sufficient detail has already been given to enable us to 
appreciate the triumph of photography in colour printing. 


156 


CHAPTER XI 


PHOTOGRAPHY AND THE 
CRIMINAL 

Misleading photographs—The criminal’s disguise—Novel use of a 
photograph—The use of photography by the police—An early 
photograph of criminals—The true use of the finger-print system 
— An amusing cartoon — Disguise defeated — The “Kathleen 
Mavourneen ” act—Method of taking the finger-prints—Detection 
by tell-tale finger-marks—Interesting cases—Photographic en¬ 
largements—Forged documents. 

P HOTOGRAPHY plays a very important part in 
the detection of the criminal. It is true that a 
photograph is often very misleading; the portrait 
of one man might easily be mistaken for that of another. 
In the illustration facing page 118 we have portraits of 
three different criminals, any one of which might be mis¬ 
taken for the other. A portrait therefore cannot be used 
as a proof of identification. As a matter of fact, the 
photograph taken of a criminal at the time of his dis¬ 
missal from prison may have no apparent connection with 
a photograph of the same man taken a few months later. 
A good illustration of this fact has been given me by 
the authorities at New Scotland Yard, London; this is 
shown opposite page 108. 

In this illustration there are only five different men’s 
photographs, but there are two photographs of each man, 
the pairs of portraits being distinguishable by the 
157 


PHOTOGRAPHY 


manner in which they have been mounted. It is a 
curious fact that the photographs in the lower row were 
all taken some time after those in the upper row. Take, 
for instance, the second man. His photograph shows 
him as an elderly gentleman, with grey hair and grey 
beard. When he fell again into the hands of the author¬ 
ities, some twelve months later, his appearance was that 
of a much younger man, with black hair and black 
moustache, as shown in the lower illustration. It would 
be quite impossible to identify these five men by means 
of their previous photographs. We shall see later how 
the finger-print system is a sure means of identifi¬ 
cation. 

I recollect a case in civil life where a photograph was 
used in place of the name upon a postal packet. An 
amateur had photographed a regiment of soldiers as they 
left for South Africa at the time of the Boer War. The 
photograph turned out to be a very good one, and the 
photographer was sorry that he did not know any one in 
the regiment to whom he might address a copy of the 
picture; indeed, he did not even know the name of the 
regiment. He adopted a novel method of addressing 
the packet containing some copies of the photograph. 
Selecting one of the men, whose face was very clear, he 
cut this man’s photograph out of one of the copies, and 
gumming it to the front of the envelope, he simply 
addressed the packet:— 

“ To (photograph), 

Serving in the Field, 

South Africa.” 


158 


AND THE CRIMINAL 


The packet reached its intended destination in safety. 
No doubt the military authorities could tell the parti¬ 
cular regiment from the photograph shown, and those 
commanding the regiment were able to hand the packet 
to the man whose photograph was exhibited on the outer 
cover. 

Although the criminal may disguise himself, the police 
authorities continue to photograph their prisoners, and 
these portraits very often help them to lay hands on some 
one that is “ wanted.’ 1 They take both a full-face portrait 
and a profile, and then place the two together on one 
card. At some police centres only one photograph is 
taken, but this shows the full face and at the same time 
the profile in a looking-glass in the picture. The effect is 
not so natural as that of the two separate photographs, 
and the looking-glass has been abandoned at head¬ 
quarters, two separate photographs being taken. 

Word may be sent to Scotland Yard from some distant 
town informing them that some mischief is being done, 
perhaps on a large scale. From the description of the 
methods adopted in the crime, the authorities may 
suspect that it is the work of one or other of a certain 
class of known criminals. The portraits of these sus¬ 
pected persons are looked out and sent down to the 
distant town, no mark whatever being put upon the 
photographs. Inquiries are made in the neighbourhood 
as to whether any of those men in the photographs have 
been seen going about. Perhaps quite a number of 
people recognise one particular portrait as being very like 
some one they have seen lately in the town. This helps 
to put the authorities on their guard, and will enable 
i59 


PHOTOGRAPHY 

the police to keep their eyes upon the suspected 
person. 

Then again the police in one district may want a parti¬ 
cular criminal, but he has fled the town. Copies of his 
portrait are sent out to other centres, so that a look out 
is kept for the “ wanted 11 man. Every police centre has its 
portrait “ gallery ” or album, with the contents of which the 
detectives seek to become familiar. The detectives have 
good memories for faces; that is part of their everyday 
business. Passing along a busy street, a detective 
observes a stranger whose face has been imprinted upon 
his memory by means of a photograph. He cannot tell 
for what or by whom the man is wanted, but he is so sure 
that he is wanted somewhere that he has the man arrested 
and taken to the police station. After lodging the man 
in a cell as a suspected person, the detective consults his 
“ gallery” of photographs. At first he cannot find out 
where the man is wanted. Several times he brings the 
man from the cell to compare him with some photograph, 
the prisoner submitting good-naturedly, “ quite sure the 
detective has made a mistake.” At last the detective 
does find the portrait he wants, and on showing it to the 
prisoner he acknowledges that the game is up. The real 
criminal may be said to behave in quite a gentlemanly 
manner when he is cornered. Unfortunately he looks 
upon his crime as his business; he tries all possible means 
to evade the police, but when he is caught and identified, 
then he has played his last card. 

In the illustration facing page 58 is shown the first 
photograph of criminals taken in Glasgow. This photo¬ 
graph has already been referred to in another chapter as an 
160 



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AND THE CRIMINAL 


illustration of Scott Archer’s positives on glass. This 
photograph is made up in a little frame just as the 
daguerrotypes were, and on the back of the frame there is 
an inscription which reads :— 

“No. 1. James Martin Lindsay, dirty thief. 1 

No. 2. James Brown Cummings, pickpocket. 

No. 3. Peter Hasson, pickpocket. 

No. 4. John McCrae, tailor (associate of thieves).” 

Unfortunately there is no date upon this photograph, 
but there is no doubt that it was taken at least half a 
century ago. 

We have seen that, despite the unreliability of a 
portrait, photography does serve a useful purpose in the 
detection of the criminal. Even if the criminal has dis¬ 
guised himself considerably, there is often a drooping lip, 
a cocked nose, or some particular formation of the head 
which points the man out to the watchful detective. The 
proper value is thus put upon portraits by the police. 
They cannot bring forward a photograph of a person 
previously convicted, and say to the Court that the 
present prisoner is the same man as was convicted for 
another crime. This would be a dangerous practice. 
Some one might be willing to swear in all good faith that 
the two were the same person. There have necessarily 
been cases of mistaken identity in time past; the inno¬ 
cent have suffered for the guilty. No one is more un¬ 
willing that this should happen than the police authorities 
themselves, and now with the modern finger-print system 

1 The terra “ dirty thief” is still a common one in the police force 
in Scotland. It signifies a low type of thief who would not hesitate 
to use violence on all occasions. 


L 


161 


PHOTOGRAPHY 


they can confidently say that there remains no possibility 
of mistaken identification. The public and the criminal 
may rest assured that now no error can possibly be made 
in identifying a former criminal. 

First and foremost I would like to point out that the 
finger-print system is not primarily concerned with the 
detection of criminals by means of finger-marks accident¬ 
ally left on articles which they have handled at the place 
of the crime; that is merely a side issue, and altogether a 
minor point. I remark this because I have heard it 
repeatedly said that the finger-print system is doomed 
owing to the fact that criminals may wear gloves and 
thus defy detection. 

An amusing cartoon was shown in one London journal. 
It depicted a youthful burglar, impatient at the time 
wasted by his older and more experienced employer in 
putting on a pair of gloves before starting to work. 
The youth taunts his master with becoming a “ dandy,' 1 
whereupon the experienced cracksman tells the lad that 
when his finger-prints become as well known to the 
police as his own are, then the lad will take to wearing 
gloves also. 

Let the criminal wear his gloves; he will certainly 
leave no tell-tale finger-marks behind him. If perchance 
he is seen outside a building with gloves on, the local 
policeman will know what he is up to. In any case the 
authorities at New Scotland Yard will not be alarmed for 
their finger-print system. The real work of the depart¬ 
ment is for the identification of criminals. What the 
authorities profess to do is to take the finger-prints of every 
criminal passing through their hands, and at any future 
162 


AND THE CRIMINAL 


time they will be able to identify that man or woman by 
again taking their finger-prints and comparing them with 
the previous records. 

For instance, the Glasgow police catch a man at some 
mischief; it only happens to be a minor offence, but they 
suspect the man is not a first offender, although he is un¬ 
known to them. He says he is “John Smith,’’ 1 and so on, 
but it really makes no difference what name he chooses to 
select, nor how cleverly he may have disguised himself, he 
can easily be identified. The Glasgow police take an im¬ 
pression of his finger-prints, and post these to the 
Registrar of Habitual Criminals at New Scotland Yard. 
When the prisoner is brought before the magistrate, a 
short remand is asked so that inquiries may be made con¬ 
cerning the prisoner. This enables the police to have 
Scotland Yard's reply. The reply received may be that 
the prisoner is not “ John Smith, 11 but “ Jeremiah Jones, 11 
who has a long list of previous convictions entered up 
against him. Indeed, his record is so bad, that instead of 
being treated lightly as a first offender he is sent to penal 
servitude, and rightly so, for it is quite evident that the 
man has no intention of trying to live an honest life. His 
only concern is to evade the police. It is obvious that 
but for this system of identification the man might have 
succeeded in passing himself off as “John Smith, 11 and 
might soon have been once more at liberty to practise his 
degrading crime. 

Not very long ago we were all shocked to hear of the 
terrible murder of a whole family of innocent people. 
Suspicion fell upon a man who had previously had some 
business transactions with the father of the family. The 
163 


PHOTOGRAPHY 


murder was of such an atrocious nature that it was 
evident that it was the work of some desperate character. 
The suspected person, however, was only known as a 
quiet-living person. His finger-prints were taken, and 
despite the fact that one finger could not be included in 
the record owing to serious inflammation, the experts had 
no difficulty in identifying the prisoner with a man who 
had previously undergone penal servitude, and who, while 
in prison, had made a very desperate attempt to escape. 
The man was ultimately proved to be the guilty person. 

When the system of identification of criminals by 
finger-prints was introduced into Australia a few years 
ago, the act authorising its use was christened “ The 
Kathleen Mavourneen Act” by the criminal class. For 
the immediate effect of the Act was to drive the habitual 
criminals out of the country. The returns for the New 
South Wales gaols since the introduction of this Act make 
most impressive reading. The number of inmates was 
steadily reduced, month by month, and in less than two 
years the total number had decreased by about one-fourth 
of the whole. 

A large number of Australia’s habitual criminals went 
across to New Zealand, where there was no finger-print 
system. There the ingenious criminal might succeed from 
time to time in hoodwinking the police, and when caught 
still pass himself off* as a novice in crime. The influx of 
these criminals was so great that New Zealand was com¬ 
pelled to adopt the finger-print system. 

By what means are the finger-prints recorded ? Not by 
photography, as some have supposed, although photo- 
164 


AND THE CRIMINAL 


graphy does play an important part in the detection of 
criminals by tell-tale finger-marks. The method of 
recording finger-marks is really very simple. The prisoner 
is taken to a table upon which lies a flat metal plate 
covered with printer’s greasy ink. First of all the 
prisoner’s right thumb is placed on the inked plate, and 
the thumb is then used as a miniature garden roller. The 
official in charge gives the prisoner’s thumb a rolling 
motion, so that the whole front of the thumb comes 
in contact with the inked plate. In this way the thumb 
lifts enough ink to give a good impression of its ridges 
upon paper. A special form is provided on which a 
separate space is marked off for each finger. In making 
the impression upon the paper the thumb is given the 
same rolling motion, so that a record of all the ridges 
upon the front of the thumb may be obtained. This is 
called a “rolled impression.” Each finger is in turn 
rolled upon the inked plate and then an impression is im¬ 
mediately taken on the paper form. After the ten spaces 
have each received a rolled impression of the correspond¬ 
ing finger, there still remain two large spaces to be filled 
in. In one of these a “ plain impression ” is taken of the 
four fingers of the left hand together. A plain impression 
is taken by merely laying the fingers upon the inked plate 
and then flat upon the paper form. The four fingers of 
the right hand are made to give a similar plain impression 
in the other space. The object of these plain impressions 
made simultaneously is to enable the expert to see that 
the person taking the rolled impressions has recorded each 
finger in the correct space allotted to it. 

The record is now complete, but the authorities place 
165 


PHOTOGRAPHY 


still one more safeguard against any possibility of error. 
If the records of several prisoners’ finger-prints were 
being taken at one time, there might be a somewhat 
remote chance of the official mixing the papers before 
they were signed by the prisoners. To make assurance 
doubly sure, the prisoner signs the paper as soon as the 
form is complete, and beneath his signature he gives 
another rolled impression of his right fore-finger. This 
may be compared with the impression of the same finger 
in the record. 

Imagine a collection of the finger-prints of about one 
hundred thousand different criminals, stored at Scotland 
Yard! What a search when the record of “ John Smith ” 
arrives to be identified! There is no use in relying upon 
a name index, for many a criminal’s name is legion. 

It will be apparent that the value of the finger-print 
system will depend entirely upon the facility with which 
the multitude of records may be referred to. One of the 
paper forms with complete finger-prints arrives from some 
distant town. It gives the prisoner’s ten finger-prints 
very clearly, but the chances are that the name given is 
an “ alias.” How then is the registrar to begin a search 
among the thousands of records in his cabinets ? 

The classification of finger-prints introduced by Sir 
Edward Henry, the Commissioner of the London Metro¬ 
politan Police, is a most ingenious one, but as photo¬ 
graphy plays no part in this branch of the subject, we 
must pass it over. It may be of interest merely to note 
that the different patterns of ridges are divided off* into 
separate classes, described as whorls (circular patterns), 
loops , arches , and composites (mixtures of the three former). 

166 


AND THE CRIMINAL 


A definite numerical value is given to each whorl, accord¬ 
ing to the finger upon which it occurs, and so on. Any 
reader who is desirous of seriously following out the full 
method of classification will find the particulars clearly 
stated in Sir Edward Henry’s textbook upon the subject 
of finger-print classification. 

I was fortunate in seeing some records arrive at Scotland 
Yard for identification. One of the experts opened one of 
these and in an incredibly short time he put down all the 
values, etc., marking the form with its complete classifica¬ 
tion number. Looking at the figures, he went straight to 
a certain pigeon-hole in a certain row in the cabinet, and 
took from it a file or bundle of records. He then selected 
a certain sub-division, and taking this by itself he quickly 
ran over the handful of records in similar fashion to a 
banker handling bank-notes. He soon came to the par¬ 
ticular number for which he was searching, and taking it 
out from the bundle, he laid it upon the table beside the 
record which had arrived by post for identification. 
There could be no doubt that the two records were 
identical. Ever so careful an examination could not 
discover any difference. It is a matter of no moment 
whether or not the two records bear the same name. The 
incoming record may be marked as that of “John Smith,” 
but it is perfectly clear that he is one and the same 
individual as “Jeremiah Jones.” 

The police authorities who have caught the man in 
some distant town are then informed of the man’s pre¬ 
vious record, and he is dealt with accordingly. If Scot¬ 
land Yard have the man’s portrait, which very probably 
they have, they post this as well as the official description 
167 


PHOTOGRAPHY 


of the man's person. Poor “ John Smith ” is fairly cor¬ 
nered ; he cannot by any possible means disguise his tell¬ 
tale finger-prints. 

The absolute reliability of the finger-print system 
depends upon the fact that the formation of these ridge 
patterns is unchangeable, and persists throughout a life¬ 
time. There will necessarily be a difference of size 
between infancy and old age, but the complex detail of 
the pattern never alters in the least. Indeed, a person 
may be identified after death by means of the finger¬ 
prints, if a previous record has also been taken. If 
Rameses II, the ancient king of Egypt at whose court 
Moses was brought up, had left us a record of his finger¬ 
prints, we could have identified his mummy even now. 

It sometimes happens that when a prisoner knows that 
his finger-prints are to be taken, he will rub the points of 
his fingers very vigorously upon the walls or floor of his 
cell, till he tears the skin and causes the fingers to bleed. 
As a rule he only damages the tips of his fingers, which 
do not come in contact with the paper record. Even if 
a criminal removes the ridges on his fingers by means of a 
fine file, it only requires a little time for the ridges to re¬ 
appear, and exactly the same complex design is again 
formed. Here is a true individuality! The prisoner’s 
appearance may be altered as much as he chooses; time 
may make very marked changes in his features; the 
colour of his eyes may even alter; his name may change 
with every day of the year; all these factors make no 
difference whatever in the modern means of identifying 
the man ; his finger-prints are even more unalterable than 
were the laws of the Medes and Persians. 

168 


AND THE CRIMINAL 


The finger-print system was used in a somewhat 
modified form in the Indian Civil Service for many years 
before it was introduced into Great Britain as a means 
of identifying criminals. The Post Office authorities in 
India found many cases of personation in connection 
with examinations for appointments. One man would 
obtain the doctor’s certificate, passing himself off as some 
other individual who meant to go up for the written 
examination, but feared it impossible to obtain a doctor’s 
certificate. This was put a stop to by the introduction of 
a simple finger-print system. 

It is quite possible that similar deceptions are practised 
in other countries. I know at first hand of one case where 
a man from a distant district got the local schoolmaster 
to go to the capital to pass a competitive examination 
in the name of the would-be applicant. Fortunately in 
this particular case the deception was discovered at the 
time of examination. 

In India it was found that at the death of a pensioner 
some relative had often succeeded in personating the 
dead man, and in this way the Government had been 
cheated. The finger-print system soon put a stop to this 
deception, which neither a good recollection of faces nor 
photography could undertake to detect. 

We have seen how the finger-print system gives a sure 
method of identification, which cannot be claimed for 
pictures of the persons made by the camera. We now 
pass on to the side issue—the detection of the criminal by 
accidental tell-tale finger-marks, and it is here that pho¬ 
tography steps in and gives most valuable aid. 

169 


PHOTOGRAPHY 


Much useful work has been and is being done in this 
direction, but it is obvious that its scope must be limited. 
If the criminal succeeds in wearing gloves during “ busi¬ 
ness hours,” this branch of the work will certainly be cur¬ 
tailed, but I should imagine that the “ light-fingered 
gentry ” would find gloves of any kind a serious handi¬ 
cap. 

On one occasion a burglar entered a London mansion, 
helped himself to what articles he desired, and, presum¬ 
ably catching sight of the uncleared supper-table, he 
drank a glass of wine. On the glass the thief left two 
clear finger-prints, and by means of these the authorities 
at Scotland Yard were able to say that the thief was a 
certain notorious criminal. 

It is quite evident that two finger-marks do not give a 
complete index to the place in the cabinet where this parti¬ 
cular criminal’s record will be found. The search, however, 
is made possible by the fact that the very nature or 
method of the crime suggests certain criminals to the 
authorities. It only remains to compare the tell-tale 
finger-marks left by the culprit with the recorded impres¬ 
sions of all probable miscreants. 

To examine the faint marks upon the glass would be a 
rather hopeless task, but here the camera is called into 
play. A photograph is taken of the finger-marks. A 
very light powder may be dusted over the glass in such a 
manner that the powder will stick to the ridges and 
make the complex design more visible. At head-quarters 
this method of dusting on a powder has been abandoned, 
the authorities preferring to arrange the light falling upon 
the .mark in such a manner that a good photographic 
170 


AND THE CRIMINAL 

impression is obtained without the artificial addition of 
powder. 

It is wonderful how a faint image may be gradually 
built up into a strong one. Professor Reiss, of Lau¬ 
sanne University, has sent me a photograph giving a 
clear impression of the ridges upon the palm of a bur¬ 
glar’s hand. The thief had touched the door of a room 
with the palm of his left hand, but the impression left 
was very slight, being, in fact, almost invisible to the eye. 
This faint mark was photographed, and the result was 
a rather weak negative. By making a second stronger 
negative from this one, and from this a third and a 
fourth, a good strong negative was finally obtained. The 
final photograph shows all the detail of the ridges, and it 
served to identify the criminal. 

Another great value of photography in connection with 
finger-prints is that it provides a reliable method of en¬ 
larging the complex pattern to any desired size, so that 
the formation of every ridge in the pattern may be 
followed. The tell-tale finger-mark is photographed and 
then enlarged a thousandfold, so that not only every 
divergence of the ridges, but the very sweat-pores may 
be seen. Then the finger-print from the record of the 
suspected person is photographed and enlarged to exactly 
the same size. With these two enlargements before one 
there can be no possible mistake. Even a non-expert 
could say definitely whether or not these two photographs 
were identical. When the case is being submitted to a 
judge and jury the two photographs are marked off, as 
shown in the illustration facing page 160. The left-hand 
photograph is of an impression found upon a piece of 
171 


PHOTOGRAPHY 


glass, the finger-mark having been made by the burglar in 
entering some premises. The photograph to the right 
hand is a similar enlargement of an impression taken 
from the criminal’s right fore-finger. The straight lines 
drawn upon the two photographs indicate identical points 
in both, and the Court has no difficulty in accepting this 
evidence, which proves the two finger-prints to have been 
made by the one finger. 

I am indebted to the authorities at New Scotland Yard 
for these and the other illustrations in connection with 
this chapter. The photographs on the opposite page were 
taken in connection with the well-known Deptford “Mask” 
Murder; the trial of this case was reported in The Times 
(London) on the 8th of May, 1905. The first photo¬ 
graph shows the cash-box upon the tray of which a 
finger-print was found. The mark cannot be readily dis¬ 
tinguished in the small reproduction shown here; it is 
seen more easily upon the original photograph. The 
finger-mark is on the upright face of the tray to the 
right-hand side. A photographic enlargement of this 
finger-print is shown in the left-hand lower illustration, 
while a similar enlargement of an inked impression taken 
from the prisoner’s right thumb is placed alongside for 
the purpose of comparison. Other evidence was brought 
forward and the criminal was proved guilty. 

In this case the tell-tale finger-print was only used 
to show that the prisoner had handled the cash-box, 
which had been found open at the scene of the murder; 
it was not used as a means of discovering who the culprit 
was. 

It may be of interest to mention two other cases, of 
172 



By permission oj the authorities at New Scotland Yard 

Finger-print found on Cash-box 

The left-hand lower illustration is a photographic enlargement of the finger-mark 
found upon a cash-box left at the scene of a noted murder. The neighbour photo¬ 
graph is of the prisoner’s finger-print taken on paper. The general similarity is 
apparent. (See chap, xi.) 

















AND THE CRIMINAL 


different types, in both of which the tell-tale finger-prints 
did lead directly to the detection of the criminals. 

A burglar entered a house by removing a pane of 
glass from a basement window. On the glass taken from 
the window-frame were the imprints of a right fore-finger, 
right middle finger, left thumb, left fore-finger, and left 
middle finger. These were all imprinted in their natural 
sequence, so that the search was made a comparatively 
easy one. The glass was immediately taken to Scotland 
Yard, where it was photographed. The tell-tale finger¬ 
prints enabled the experts to look out the record which 
corresponded with these. There was not the slightest 
doubt that this criminal was the guilty person. Only a 
few hours elapsed after the police were informed of the 
burglary before the thief was located and arrested with 
the stolen property in his possession. He pleaded guilty; 
he could hardly do otherwise. No doubt he would be 
surprised that the police should “spot” him so very 
quickly as the man “ wanted.” 

The other case to which I shall refer will show how a 
guilty person who is not a known criminal may be 
detected. A sealed packet containing bank-notes was 
sent through the post, and when it arrived at its destina¬ 
tion it was found that half of the notes were missing, 
although the packet had no appearance of being tampered 
with. When the packet was examined it was found that 
one of the seals had been remade, and the melted wax had 
taken the distinct impression of a thumb. Each person 
through whose hands the packet had passed was asked to 
allow an impression of his thumbs to be taken on wax. 
There happened to be seven persons in all who had handled 
i73 


PHOTOGRAPHY 


the packet. The records taken of the thumb-prints were 
immediately photographed and then a set of larger photo¬ 
graphs made of these. The tell-tale finger-print upon the 
sealing-wax was enlarged to the same size. 

A glance at the enlargements showed that five of the 
seven records had no resemblance whatever to the guilty 
mark. One of the two remaining records looked just at 
first something like the tell-tale impression, but on 
examination was seen to be quite different. The one 
remaining record, however, was unmistakably identical; 
every part of the complex pattern coincided with mathe¬ 
matical accuracy; the guilty person had undoubtedly 
been detected. 

From the cases quoted we see that the tell-tale finger¬ 
prints may be left on glass, metal, paint, or sealing-wax. 
There are other cases in which the detection of the 
criminal has been possible from impressions left on paper, 
wood, ornaments, etc. We must not think, however, 
that any finger-marks or smudges are good enough for 
identifying the culprit; there must necessarily be a clear 
impression of the ridge pattern, or the finger-mark is of 
no use. The police might cut out a piece of lead water- 
pipe, upon the painted surface of which some intruder 
had left some dirty finger-marks, but by a preliminary 
examination of these with the aid of a magnifying glass 
it should have been apparent that there was no impression 
of ridges at all. The fingers had merely been drawn 
across the pipe, and had not been firmly pressed upon it 
and then lifted. It would be asking too much of any 
expert to read these finger-marks; there is nothing to 
read. Some discretion must therefore be used in deter- 


74 


AND THE CRIMINAL 


mining whether or not it is worth while cutting out bits 
of useful property which happen to have been handled by 
a burglar. A simple examination through a magnifying 
glass will show whether or not a record of the ridges upon 
the fingers has been left. 

There are other directions in which the camera has 
proved of service in detecting crime. When a man forges 
a signature he does not write it straight off without 
stopping, but does it piece by piece slowly, as though 
he were painting it. If such a forged signature is photo¬ 
graphed and enlarged it shows every mark of the pen 
as it commences and finishes each stroke. The autho¬ 
rities at New Scotland Yard have made extensive use 
of photography in detecting forged documents in this 
manner. 

I have also received some photographs from Professor 
Reiss, of Switzerland, showing how falsified documents 
have been detected. These photographs could not be 
satisfactorily reproduced by half-tone printing blocks, 
so I shall merely mention the facts relating to them. 

In one case a document was suspected of having been 
tampered with, but the eye could discern no alteration. 
When one part of the document was photographed and 
an enlargement made, it was quite clear that the figures 
25 had been erased from the paper. 

In the second case the forger had added a tail to the 
letter “o” so that it was converted into a “g.” No 
addition could be detected by the eye, but the enlarged 
photograph distinctly showed that this tail of the u g r * 
was quite different from all the rest of the writing. 


i75 


CHAPTER XII 


PHOTOGRAPHING THE INVISIBLE 


Fox Talbot and invisible rays—An ordinary portrait taken in total 
darkness—Photographic sensation in 1896—Curious ideas concern¬ 
ing the new photography—A demonstration with the fluorescent 
screen—Soft and hard tubes—Some experiments with a camera— 
Why no camera is required—Why the fluorescent screen must be 
used in the dark—Subjects that can be “X-rayed”—An impos¬ 
sible case—A visit to a large hospital—The applications in practice 
—An unerring witness—Further applications—Double photo¬ 
graphs versus single ones—Risk of burning—Imitation gems. 

T HE title of this chapter may seem rather mys¬ 
terious ; I hasten to assure the reader that it has 
no reference to any attempt at spirit photography. 
I am not a believer in ghosts, excepting the old-fashioned 
spectre with his turnip head. 

It is remarkable that we are able to photograph things 
which are invisible to our eyes, and yet we shall find that 
the idea of doing so is almost as old as photography 
itself. 

In the earlier part of this volume I had occasion to 
refer repeatedly to The Pencil of Nature , published by 
Fox Talbot in 1844. This contains one very curious 
chapter, or part, relating to invisible rays. Any one who 
has access to a copy of The Pencil of Nature will find this 
part under the title “ Scene in a Library.” I made men¬ 
tion of this part in an earlier chapter, remarking that 

176 


PHOTOGRAPHING THE INVISIBLE 

the scene in a library consisted of two shelves of books 
taken at close quarters. Talbot issued The Pencil of 
Nature in parts, giving with each portion as it was pub¬ 
lished an original photographic print. The text of each 
part usually had special reference to the subject of the 
picture accompanying it. But as there could not be 
much to say concerning two rows of books, from a photo¬ 
graphic point of view, it is not surprising to find that 
the text of this particular part has no reference to the 
plate issued with it. I think it will be of general interest 
to give this part in Talbot’s own words:— 

“ Among the many novel ideas which the discovery of 
photography has suggested, is the following rather curious 
experiment, or speculation. I have never tried it, indeed, 
nor am I aware that any one else has either tried it or 
proposed it, yet I think it is one which, if properly 
managed, must inevitably succeed. 

“ When a ray of solar light is refracted by a prism and 
thrown upon a screen, it forms there the very beautiful 
coloured band known by the name of the solar spectrum. 

“ Experimenters have found that if this spectrum is 
thrown upon a sheet of sensitive paper, the violet end of 
it produces the principal effect: and, what is truly 
remarkable, a similar effect is produced by certain invisible 
rays which lie beyond the violet, and beyond the limits of 
the spectrum, and whose existence is only revealed to us 
by this action which they exert. 

“Now I would propose to separate these invisible rays 
from the rest, by suffering them to pass into an adjoining 
apartment through an aperture in a wall or screen of 
partition. This apartment would thus become filled (we 
177 


M 


PHOTOGRAPHING THE INVISIBLE 


must not call it illuminated) with invis bie rays, which 
might be scattered in all directions by a convex lens 
placed behind the aperture. If there were a number of 
persons in the room, no one would see the other; and yet 
nevertheless if a camera were so placed as to point in the 
direction in which any one were standing, it would take 
his portrait, and reveal his actions. 

“ For, to use a metaphor we have already employed, the 
eye of the camera would see plainly where the human eye 
would find nothing but darkness. 

“ Alas! that this speculation is somewhat too refined to 
be introduced with effect into a modern novel or romance; 
for what a denouement we should have, if we could suppose 
the secrets of the darkened chamber to be revealed by the 
testimony of the imprinted paper. 11 

Thus wrote our illustrious Fox Talbot, who was not 
only an inventor, but a very learned man. I think the 
suggested arrangement will be quite clear to all. A beam 
of light, in an otherwise dark room, is to fall upon a 
prism of glass so that a spectrum is formed. This prism 
is to be so placed, against a dividing partition of a second 
dark chamber, that only the dark part of the spectrum 
will be opposite an aperture in the partition. The 
coloured bands of light are thus prevented entering the 
inner dark chamber. The invisible rays which affect a 
photographic plate do enter, and it is suggested that a 
photograph might then be taken in the ordinary way. 
The idea is curious; that one should sit in a totally dark 
room to have one's portrait taken. Talbot believed that, 
“if properly managed, it must inevitably succeed.” I 
have made a search to find if any person has ever had an 
178 


PHOTOGRAPHING THE INVISIBLE 


actual portrait taken in this way. I have been very much 
interested to learn that such a portrait has been taken 
by Mr. Edgar Senior, of the Battersea Polytechnic. A re¬ 
production of this is shown in the illustration opposite 
page 196. The source of the dark rays was an arc lamp, 
and all the visible radiations were cut off at the lens by 
means of special screens invented by Professor R. W. 
Wood. The exposure was five minutes. 

Most of us will remember the sensation caused in 
the opening days of 1896, when it became known that 
Professor Rbntgen, of Wurzburg, had actually photo¬ 
graphed the living skeleton of the hand, etc. The very 
weirdness of the subject fascinated us. Many people, 
believing that the photographs were taken by a camera in 
the usual way, spread fantastic ideas abroad. I remember 
seeing some pictures drawn by students in the University 
of Glasgow to represent the new photography. One 
picture in particular I remember ; it was of four skeletons 
sitting in life-like attitudes around a small table, smoking, 
drinking, and playing cards. One even heard, at the very 
outset, that the photographer did not require to be in 
the room at all, for his apparatus would work, with per¬ 
fect ease, through stone walls, and so on. 

For our present purpose it does not concern us how the 
Rbntgen rays are produced; I have dealt already with 
that subject in some detail in one of these Romance 
volumes —The Romance of Modern Electricity —and else¬ 
where. It will be sufficient to remark here that we 
require a battery or other source of electric current, an 
induction coil to increase the electric pressure, and a 

179 


PHOTOGRAPHING THE INVISIBLE 


specially constructed vacuum tube—known as an X-ray 
tube. When the current is turned on, we get X-rays 
thrown off from a little metal target in the tube. 

If we were to bring an unopened box of ordinary 
photographic plates within the field-of-action of the X-ray 
tube while at work, we should find that the plates were 
all fogged, just as though they had been exposed to day¬ 
light. If a photographer were asked to develop these 
plates, not knowing what had happened, he would say 
that light had got at the plates and completely spoilt 
them. It will be clear, therefore, that these mysterious 
X-rays have similar actinic or chemical properties to 
ordinary light; more than that, they can pass through 
the light-proof box containing the plates. 

If one wanted to explain to some country cousin how 
an ordinary photograph is taken, one might get the 
friend to look upon the ground-glass focussing screen of 
the camera and see there the image of the objects to be 
photographed. One would then explain that, in order 
to take a photograph, the ground-glass screen was re¬ 
moved and a sensitive photographic plate placed in its 
stead. The image would then fall upon the chemicals on 
the plate and cause a chemical change to take place. 
When the plate is developed it will give a record of all the 
variety of light and shade that fell upon it. 

To explain how an X-ray photograph is taken, the 
best plan would be to take a fluorescent screen and let 
the country cousin see that when the X-rays fall upon it 
they cause the whole screen to fluoresce or become 
luminous. Where is the camera ? A camera is of no use 
with these rays; they would not be focussed by a le*is, 
180 



Photo by 


An X-ray Photograph 


John Trotter, Glasgow 


On the middle finger there is a real diamond ring; the stones are quite transparent to 
the Rontgen rays. On the fore-finger is an imitation.diamond ring; the stones are quite 
opaque to the rays. Other points of interest are explained in the text. (See chap, xii.) 












PHOTOGRAPHING THE INVISIBLE 


and they would defy the light-proof body of the camera, 
passing easily through the wood and leather. In taking 
an ordinary photograph, we allow light to fall upon the 
object of which we desire to take a picture. The light 
is reflected by the object, passes through the lens of the 
camera, and falls upon the sensitive plate. 

Suppose we try to photograph an object by the X-rays 
in the same manner as we do by ordinary light. What 
will happen ? We let the X-rays fall upon the object; 
they are not reflected back to the camera; they go 
right through the object. What! through the human 
body? They do, but they meet with some resistance. 
The clothing offers very little resistance ; the flesh is 
slightly more opaque to the rays, the bones more so. 
The rays are not reflected like rays of light, so we may 
dispense at once with the idea of a camera. How, then, 
are we going to get a photograph ? We must go to the 
back of the object, and catch the rays there after they 
have passed through the body. As already suggested, we 
shall understand the matter better if we, in the first in¬ 
stance, use a fluorescent screen in place of a photographic 
plate. 

We set the X-ray tube to work, placing it in front of 
us. We then let the invisible rays fall upon one of our 
hands; we see nothing. We then place the fluorescent 
screen with its coating of fine crystals between us and the 
hand. The screen is a simple wooden frame, upon which 
is stretched a piece of paper carrying on the one side the 
coating of crystals, and on the other side a lining of 
black cloth or paper. We turn the black back of the 
screen to the X-ray tube, place the hand right against 
181 


PHOTOGRAPHING THE INVISIBLE 


the back of the screen, and then view the effect upon 
the chemicals on the front of the screen. We see that 
the rays are getting through the flesh of the hand with 
no great resistance; there is only a shading of the light 
at those parts. The bones, however, are much more 
opaque, so that we see them very distinctly as darker 
shadows. The rays, getting through between each finger 
joint, cause each joint to stand out very distinctly. We 
further observe that the effect is not that of a flat 
shadow ; the bones really appear rounded. This effect is 
produced by the rays getting more easily through the 
sides of the bones than through the thicker centres. 
How very distinctly a ring upon the finger is seen; it is 
not only much blacker than the bones, but the complete 
circle of the ring is clearly seen. We are seeing part of 
the ring through the bone. Here we have a most useful 
property of these rays: we can see through and through. 

As I have already remarked—we have almost ceased to 
wonder at these facts. But here comes a well-educated 
lady who has never happened to see an X-ray apparatus 
at work. We ask her to place her hand and forearm 
behind the screen, but she shrugs her shoulders; she 
would rather see some other person’s skeleton. We place 
behind the screen, unopened, a small hand-bag, which she 
happens to have with her. We see that she has been 
shopping, for there is a small photograph frame with 
metal ornamentations at the corners. Behind this again 
we see a small case containing various sizes of scissors, etc., 
and in one corner of the bag is a packet of pins. At the 
bottom of the bag is her purse, the contents of which are 
clearly seen. The lady is very much amused at the idea 
182 


PHOTOGRAPHING THE INVISIBLE 


of seeing what is in her purse, while it not only remains 
closed, but is further secluded inside her hand-bag. 

After seeing some other person’s bones, the lady is quite 
pleased to view her own hand and forearm. She has not 
quite caught the meaning of the experiment, for she is 
about to take her glove off, when we tell her that the 
X-rays laugh at trifles such as gloves. There are the 
buttons of the gloves, the rings on the fingers, and a 
wrist bangle which appears as a continuous hoop, although 
it encircles the arm. But what amuses our friend most 
is that every hook on the sleeve of her blouse is perfectly 
distinct, although she has a thick winter jacket on the 
top. There is a pin apparently in the outer jacket, and 
there above the wrist are some buttons of her outdoor 
jacket. These buttons are at the back of the arm, so 
that they are being seen through the bones. What a 
pity Charles Dickens could not have lived to see this! It 
will be remembered how in his Christmas Carol he makes 
old Ebenezer Scrooge see the ghost of his late partner, 
Jacob Marley. As Scrooge looked the phantom through 
and through he could see a chain of cash-boxes, keys, and 
padlocks, completely encircling the ghost’s waist; just as 
we see the lady’s bangle completely encircling her wrist. 
But listen to what Dickens says further, concerning 
Marley’s ghost: “ His body was transparent; so that 
Scrooge, observing him, and looking through his waistcoat, 
could see the two buttons on his coat behind.” Little did 
Dickens think, when he penned these words about Mar- 
ley’s ghost, that they would become literally true. 

If we place a cage containing a rabbit behind the 
screen, we can see the whole living skeleton moving about. 

183 


PHOTOGRAPHING THE INVISIBLE 


If we try a cage of mice or white rats, we must have a 
tube which will not give too penetrating rays, or we 
shall see through the bones and all, and only have a very 
faint shadow upon the screen. The chief factor in deter¬ 
mining the penetrative power of the rays is the degree 
of exhaustion given to the vacuum tube. If the tube has 
a low vacuum, the air not having been exhausted to the 
greatest possible extent, then the electric current will 
pass more easily through the tube, but the rays produced 
will not be so penetrative. A tube of this description is 
called a soft tube. If, on the other hand, the tube has 
a high vacuum, the current has more resistance to over¬ 
come, the rays are more penetrative, and the tube is known 
as a hard tube. 

I have purposely gone into some detail with the 
fluorescent screen, as it enables one to grasp the photo¬ 
graphic part more easily. 1 

It would, of course, be possible to place a camera in 
the position from which we have been viewing the 
fluorescent screen, and then take a photograph of what 
we see upon the screen. This would not be an X-ray 
photograph; it would be a photograph of an X-ray 
screen with an image upon it. More than one experi¬ 
menter did try this in the early days of X-ray work. I 
remember one local experimenter finding on his first nega¬ 
tive, not only a picture of the screen with the skeleton of 
the hand upon it, but also an image of the front of his 
camera. He was attempting to focus the ordinary light 

1 This seeing of the bones upon a fluorescent screen was really 
prior to the new photography. Recording the image upon a photo¬ 
graphic plate was a later achievement by Professor Rontgen. 

184 


PHOTOGRAPHING THE INVISIBLE 


from the visible image on the screen, but it was evident 
that X-rays were also getting at his photographic plate. 
The fluorescent screen with its surface of chemical 
crystals was not stopping all the X-rays falling upon it. 
Some rays passed through the front of the camera, and 
therefore left upon the sensitive plate a shadow or shaded 
image of the front of the camera. This difficulty was 
overcome by placing a sheet of lead over the front of the 
camera, leaving only the lens unprotected. The light 
emitted by a fluorescent screen is not very bright, so that 
an exposure of some minutes was required. In any case a 
camera was only going to give a reduced size of photo¬ 
graph of the screen, and this is no advantage. 

If we look upon the fluorescent screen as being analo¬ 
gous to the ground-glass focussing screen in a camera, 
then we at once see the simplest method of taking an 
X-ray photograph. Follow the method in ordinary 
photography; remove the focussing screen and place a 
photographic plate in its stead. The image will then fall 
upon the sensitised plate. The analogy may at first seem 
somewhat deficient because of the absence of the camera 
in X-ray work. But in ordinary photography the camera 
is merely a dark box in which to expose the sensitive 
plate to the action of light falling upon it. The camera 
may be a cigar box with a pinhole in it, or it may be a 
darkened room with a hole in the window-shutter. In 
X-ray work it is more usual to have a darkened room as 
the camera, and in this case the source of the radiations 
(the X-ray tube) is inside the camera. Another plan is 
to form a small dark chamber in which the observer can 
«it or stand with the fluorescent screen, while the patient 
185 


PHOTOGRAPHING THE INVISIBLE 


to be examined and the X-ray operator with his appa¬ 
ratus are not in the dark at all. The patient stands 
against one of the walls of the darkened chamber, so that 
the observer can place the fluorescent screen immediately 
behind the part to be examined. The observer could 
then substitute a photographic plate for the luminous 
screen, and in this way take an X-ray photograph. But 
looking upon the darkened chamber as a camera, what 
purpose is it serving as far as our X-ray photograph is 
concerned ? There is no focussing required; we merely 
place the photographic plate immediately behind the 
object to be photographed. The camera is therefore 
only a darkened chamber for holding the sensitive plate. 
A black paper envelope will therefore serve the same pur¬ 
pose. All we need to do in taking an X-ray photograph 
is to enclose the photographic plate in a light-proof 
envelope and place this immediately behind the part to 
be photographed, the object therefore coming between 
the X-ray tube and the plate. X-ray photography is 
therefore carried on in the light, the dark camera being 
the black envelope enclosing the plate. 

It is, of course, necessary to have a darkened room 
when using the fluorescent screen. If one looks at the 
clear sky in bright daylight, one does not see the light of 
the stars because of the stronger sunlight. If one looks 
up a disused factory chimney, one then sees the stars even 
in bright daylight, because the eye is shielded from the 
direct light of the sun. In the same way one cannot see 
the image upon the fluorescent screen because of the 
brighter light in the room; the room must therefore be 
darkened, or the observer and screen must be enclosed in 
186 


PHOTOGRAPHING THE INVISIBLE 


a dark chamber. This latter method is very useful when 
children have to be examined, for the quick hum of the 
induction coil and the peculiar phosphorescent light in 
the X-ray tube are rather alarming to a child in the dark. 
It is also of advantage to the electrician to be able to see 
his apparatus. 

Referring again, for a moment, to the attempts to 
photograph the image upon the fluorescent screen with 
an ordinary camera, I recollect seeing the results of some 
experiments made with the cinematograph. A frog’s 
legs were mechanically moved behind a fluorescent screen, 
and the cinematograph camera recorded the movements 
as seen upon the screen. The idea was to show the action 
of the joints, but the results were not encouraging, the 
illumination being very deficient. 

Returning to the simple method of direct X-ray 
photography, it will be of interest to see what can and 
what cannot be photographed. The largest field is in 
photographing the bones of the human body, but many 
of the internal organs may also be seen and photographed, 
with properly adjusted apparatus. 

A paralysed gentleman paid me a visit recently to ask 
if I could take an X-ray photograph of his head, to try 
and locate in what part of the brain the seat of his 
injury lay. He had been reading of some wonderful 
surgical operations made upon the brain, and he very 
naturally desired to know if nothing could be done in his 
case, which had been the result of a sunstroke. While 
one side of him is paralysed and the power of speech is 
lost, his sense of hearing remains perfect and he is as 
clear-headed as ever. I explained to him that while it 

187 


PHOTOGRAPHING THE INVISIBLE 


was possible to photograph a bullet or other piece of 
metal lodged in the head, it was impossible to photograph 
the soft tissue of the brain, which is completely enveloped 
in the much more opaque bone. By way of illustration I 
pointed out that we could photograph a piece of metal 
enclosed in a wooden box, but that we could not photo¬ 
graph a piece of wood placed inside a metal box; the 
metal being more opaque than the wood. 

What will be of most interest to the general reader is 
to know exactly what sort of photographs are being taken 
with X-rays in everyday life. 

First of all let us, in imagination, visit one of our large 
hospitals. Here we find couches specially arranged for 
taking photographs of any part of the body. In one 
arrangement the X-ray tube is supported above the 
couch, so that the photographic plate must be placed 
beneath the patient. The photographic plate is slipped 
in below a parchment window, at the centre of the couch, 
and in this way the plate is brought close up to the 
patient. 

Some operators prefer to have the X-ray tube beneath 
the couch, the tube being then supported in a little 
carriage or truck, which may be moved into any desired 
position. In this case the photographic plate is placed 
upon the top of the patient. The patient will lie face 
downwards on this couch, instead of lying upon his back, 
as he would do on the couch shown in the illustration. 

One advantage in the couch with the tube beneath it 
is that the operator, having the photographic plate on the 
top of the patient, may lay a fluorescent screen on the top 
of the photographic plate, and thereby see that the tube 
188 


PHOTOGRAPHING THE INVISIBLE 


is giving a good image. When the operator is going to 
use the viewing screen during the time of exposing the 
plate, he must not use photographic plates made of lead 
glass, for it is opaque to X-rays. Other glass will allow 
the rays to pass through the plate and cause the screen to 
fluoresce, and at the same time record the image on the 
sensitive plate. 

What advantage is to be gained by watching the image 
on the screen while taking an X-ray photograph ? The 
operator can see how his X-ray tube is behaving. He 
knows that the exposure for a certain tube should be 
about two minutes, but tubes sometimes vary very much 
during use. If the operator sees by the screen that the 
rays are falling off in intensity, or, on the other hand, 
becoming too penetrative, he can regulate the electric 
current accordingly. He may also lengthen or shorten 
the time of exposure if necessary. 

What sort of photographs does the X-ray operator 
get ? Excellent pictures of the bones of the human 
body, such as seen in the illustration opposite page 180. 
If the reader has only seen photographs of the bones, I 
fear that his first impression, upon seeing a collection of 
photographs of other parts of the body, would be that 
they are very poor affairs. They certainly are not much 
to look at from a pictorial point of view. There is an 
absence of the clearly defined lines seen in an X-ray 
photograph of the bones, for we have not the same differ¬ 
ences of opacity. If one has expected to find an X-ray 
photograph of the heart to be anything akin to the 
illustrations of that organ, as shown in books on phy¬ 
siology, then one will be sorely disappointed. One only 

189 


PHOTOGRAPHING THE INVISIBLE 


finds a dull grey and rather indefinite mass. Yet it is 
possible to locate an enlarged blood-vessel, known as an 
aneurism. This is of great importance, as the following 
case will testify. 

A medical friend had a case sent to him in connection 
with the Workmen’s Compensation Act of Parliament. 
There was a dispute as to whether or not the workman 
had an aneurism; the doctors differed. The X-ray 
photograph, however, showed clearly that no aneurism 
was present, and its testimony could not be disputed. 

Enlargement and displacement of the heart are easily 
detected by the new photography; and while the photo¬ 
graphs are not pictures, they are of much value to the 
medical man. Without going into surgical details, I may 
merely mention that cases of tubercular lungs are photo¬ 
graphed to advantage. The surgeon may also find 
whether cancer has merely affected the soft tissue or 
has attacked the bones. 

Another very important subject of X-ray photography 
is stone in the kidney. It is sometimes very difficult for 
surgeons to tell from the symptoms whether this trouble 
really is present or not. The X-ray photographer makes 
matters quite clear, showing how many, if any, of these 
bodies are present. To the ordinary person these photo¬ 
graphs would appear at first as the result of fogged plates 
with some darker markings upon them. There is so little 
difference in the opacity of the organ itself and these 
ctggregations of salts, that the whole photograph looks 
like a dull grey indefinite mass. In order to illustrate 
the great utility of these photographs 1 may mention the 
following case. 


190 


PHOTOGRAPHING THE INVISIBLE 


A medical friend, who has had a large experience in 
such cases, had a patient brought to him in whom the 
symptoms seemed very decidedly to show the presence of 
this trouble. My friend took several photographs, and 
said that there were no foreign bodies present in the 
kidney. The patient, however, was quite positive that 
stones did exist, although the X-ray photographs failed 
to detect them. He was so certain that he insisted upon 
the surgeons performing an operation. The surgeons had 
to carry out the patient’s wishes, but on operating they 
found that, despite all the symptoms, there were no 
stones present; the X-ray photographs were confirmed as 
truthful witnesses. One X-ray photographer informs me 
that, as far as he knows, he has never yet had a case of a 
mistaken photograph. He has never sent a case to the 
surgeons saying that the trouble was present when it was 
not found to be so upon operation. 

As already indicated, the largest field of service for 
X-ray photography is in connection with the human 
framework. Many eminent surgeons will not operate 
until they see a photograph of the injured bones. Not 
only are fractures clearly shown, but also malformation 
and parts affected by disease. The surgeon may also see 
how the fractured bones are setting. This is a great 
boon. It enables the surgeon to examine a troublesome 
fracture which he has previously set without requiring to 
remove the splints, etc. In cases of fractured arms, some 
surgeons in private practice get their patients to call and 
have the injured limb photographed each day while the 
arm is setting. 

The use of X-ray photographs for detecting pieces of 
191 


PHOTOGRAPHING THE INVISIBLE 


metal in the body has already been referred to. A child 
swallows a coin, and the X-ray photograph at once 
detects the intruder. Not only does it tell whether the 
coin has stuck in the gullet or passed into the stomach, 
but it shows the exact position in which the coin has 
lodged. In the case of a child swallowing a coin, it is 
usually sufficient for the X-ray operator to examine the 
patient with the fluorescent screen, and merely note down 
the position of the coin for the surgeon without taking a 
photograph. When, however, a child swallows a toy 
bicycle or performs some other extraordinary feat, it is of 
importance to be able to give the surgeon a photograph 
to have beside him while operating. In the case of a 
coin, there is no operation further than fishing the in¬ 
truder out with a coin-catcher. The London Hospital 
did have a case of a little girl of four and a half years 
who swallowed a toy bicycle of considerable dimensions. 
With permission of the hospital authorities I used this 
photograph as the frontispiece to my Electricity of To-day. 
In time of war it is also of great service to the surgeon 
to be able to locate the exact positions of bullets in the 
body. 

Perhaps the best known of all the uses of the X-rays 
is the detection of broken needles in the hands. Before 
the days of the new photography it was a very trouble¬ 
some operation to remove these intruders. Even with 
good X-ray photographs it is not an easy task if the part 
of the needle happens to be small, and if it has only tem¬ 
porarily lodged in a place from which it can be easily 
moved along. The wanderings of a broken needle 
within the body are strange indeed, and it is in the 
192 


PHOTOGRAPHING THE INVISIBLE 


locating of the needle’s whereabouts that the X-rays are 
so useful. 

X-ray photographs are taken to locate small particles 
of metal in the eye. By taking two photographs, with 
the tube in different positions, it is possible to calculate 
the exact depth at which the foreign body is lodged. To 
emphasise the Importance of these double photographs, 
I may state one case of which I know at first hand. A 
workman, having got a small piece of brass into his eye, 
had it X-rayed in the ordinary single-photograph method, 
but on operating the surgeon could not find the speck 
shown in the photograph. Later on he had it X-rayed 
by the double-photograph method; the depth at which 
the object lay, and its exact position, were then calculated. 
The surgeon was able now to locate the miscreant, but 
unfortunately it was then too late to save the eye. 

It must be clear to all that X-ray photography is 
of very great value to the surgeon. Even the dentist 
occasionally calls this new photography to his aid. He 
may place a small photographic film inside the mouth, 
and use an ordinary X-ray tube outside. In this way he 
can photograph the roots of teeth in the jaw. 

One hears a great deal about the danger of the X-rays 
“ burning ” the flesh. There is, unfortunately, this dis¬ 
advantage, but it concerns the operator very much more 
than the patient. The patient runs practically no risk 
now in the hands of a qualified operator. The man who 
is continually working with X-rays, however, runs con¬ 
siderable risk, but it is fortunate that the X-ray operators 
are willing to expose themselves to this risk. 

This risk of “burning” is almost entirely absent from 
193 


N 


PHOTOGRAPHING THE INVISIBLE 


the practice of X-ray photography. It is only when 
very long exposures have to be made for curative purposes 
that there is any real risk. In these therapeutic cases 
every precaution is taken by using lead glass shields for 
the tubes, leaving only a small window for the rays to 
pass out by and attack the diseased part. 

A medical friend showed me some special gloves which 
were sent to him as being proof against X-rays. When a 
photograph was taken, however, of the protecting glove 
with a hand inside, the negative showed that the glove 
was not opaque to the rays. The skeleton of the hand 
was observable upon the photographic plate, which would 
not have been the case had the gloves been impervious to 
the rays. 

The surgeon may learn much by taking photographs of 
the different joints of normal bones. By a series of photo¬ 
graphs of the joints in different positions, he is able to see 
exactly how the bones forming each joint are moved. 

There are other uses to which X-ray photography may 
be put, such as the detection of imitation diamonds, 
rubies, etc. In the illustration opposite page 180 a real 
diamond ring will be seen on the first finger, the real 
stones being quite transparent, and on the middle finger 
is one with imitation diamonds, the stones being opaque. 
The difference is very marked. We might have two ruby 
rings, so like each other that no one but an expert could 
distinguish them, but an X-ray photograph would show 
the real rubies to be transparent, and the imitation ones 
of coloured glass to be opaque to the rays. 

In the photograph of the lady’s hand and forearm, it 
will be observed that the sleeve of the outdoor jacket is 
194 


PHOTOGRAPHING THE INVISIBLE 


scarcely visible; only its fancy metal buttons have been 
recorded. The hooks are on the sleeve of the lady’s 
blouse, and look rather strange without their accompany¬ 
ing eyes. The eyes were made of thread and so do not 
appear. The complete bangle encircling the wrist shows 
at one part through the bone of the arm. The glove 
buttons are seen, and what is very strange—the silk 
sewing upon the back of the glove. This I presume 
is due to the dyer having added lead to his dye in order 
to weight the silk. 


i95 


CHAPTER XIII 


MORE INVISIBLE RAYS 

All light is invisible—Photography discovers ultra-violet light—A 
puzzled photographer—A great boon to suffering man—Photo¬ 
graphing an invisible inscription—Ultra-violet rays versus X-rays 
—Photography discovers an unknown property of matter—An 
historical experiment—Radio-activity—Some interesting negatives 
—An amusing incident—Some points of interest. 

I N the preceding chapter we have considered photo¬ 
graphy by means of X-rays. These are not the only 
invisible rays which affect a photographic plate. 
Some of us were taught at school that all light is in¬ 
visible. Of course it is; we cannot see the ether, and 
therefore we cannot see any motion or vibration of it. If 
we could do so, we should then see light at night time 
far out in the universe, beyond the shadow of our earth. 
Light is passing out from the sun to the other planets 
through the dark space which we see encircling our globe 
at night. We do not see this light. It is only when the 
ether waves, called light, enter our eyes that we have 
the sensation which we recognise as due to light. This 
light may come direct from its source to our eyes, or 
it may fall upon some object and then be* reflected to 
our eyes. We do not see the light itself; we may see 
the source of light. When we speak of invisible rays, 
however, we simply mean rays which do not affect our 

196 


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MORE INVISIBLE RAYS 


sense of vision. It will therefore be understood that 
while all light is invisible, we may still use the words 
invisible rays to describe those rays to which our eyes do 
not respond. 

In the beginning of the preceding chapter we saw that 
when a beam of light was parsed through a prism and 
then allowed to fall on a photographic plate, there was a 
darkening of the plate beyond the range of the visible 
spectrum. The photographic spectrum was much longer. 
It is clear that these rays outside of the visible spectrum 
are not what we term light, and yet they must be con¬ 
tained in ordinary light, for we have nothing but a beam 
of light passing through the prism. These invisible rays 
are called ultra-violet light , and we can easily assign them 
their proper position in the photographic spectrum if we 
remember enough of our school-day Latin to know that 
ultra means beyond. These rays are beyond the violet 
end of the spectrum. 

It is only natural to ask if there are any invisible rays 
at the other end of the spectrum below the red. The 
photographic plate would seem to answer in the negative. 
Indeed, an ordinary photographic plate will not be 
affected by any part of the spectrum below green. It 
was this fact which suggested to photographers that they 
might carry on their developing processes with the aid of 
a red or orange light, instead of working away in total 
darkness as they had previously done. 

We have already seen that special photographic plates 
can be made which are sensitive to all colours, otherwise 
colour photography would be impossible. That is to say, 
we could not get a black and white record of red and 
197 


MOKE INVISIBLE RAYS 


yellow colours unless the photographic plate were sensitive 
to these rays. If an addition of an aniline dye, a pro¬ 
duct of coal tar, is made to the chemical composition on 
a photographic plate, it becomes not only sensitive to all 
the visible spectrum, but it reveals invisible rays below 
the red. These invisible rays are called infra-red , signify¬ 
ing that when a beam of light is analysed these rays are 
found below the red end of the spectrum. The photo¬ 
graphic spectrum therefore stretches out beyond both ends 
of the visible spectrum, and measures about eight times 
the length of the visible spectrum. 

These infra-red rays will, of course, take no part in 
ordinary photography, while the ultra-violet rays will do 
so. The ordinary photographer may be quite unaware of 
the presence of these ultra-violet rays. I remember, how¬ 
ever, an occasion when these rays played a trick upon a 
friend. He was photographing a black and white draw¬ 
ing made by an artist, but when reproduced the whites of 
the drawing came up impure; they looked more like grey. 
At first my friend was somewhat puzzled, but it occurred 
to him that the artist must have happened to use some 
white paint which absorbed ultra-violet light. The 
photographer was using an arc lamp to light up the pic¬ 
ture, and though this light is rich in ultra-violet light, the 
white paint did not reflect these rays back to the plate, 
while a piece of white paper would do so. The conse¬ 
quence was that the whites appeared dirty in the repro¬ 
duction. Had the photographer asked the artist to paint 
the picture again with another white paint, the artist 
would possibly have thought the request to be an absurd 
one, for the white looked as white as it could be made. 

198 


MORE INVISIBLE RAYS 


So it was to the human eye, but we are not conscious of 
the presence of ultra-violet light; it does not affect 
the eye. The photographic plate is more sensitive in 
that respect, and records the presence or absence of these 
rays. 

The photographer in this case did not require to ask 
that the painting should be repainted. He adopted an 
ingenious plan. He photographed the picture through a 
transparent liquid which absorbed all the ultra-violet 
light. This meant that no ultra-violet rays were allowed 
to enter the camera at all. It was therefore of no 
moment whether the white paint was reflecting ultra¬ 
violet rays or not. In this way a perfect copy of the 
picture was made. 

The photographic action of the ultra-violet rays was 
known in the very earliest days of photography, and, 
indeed, the discovery of the existence of these rays was 
due to their photographic action. It is these ultra-violet 
rays which have enabled us to fight that distressing 
disease known as lupus , for it is these rays which are pro¬ 
duced in abundance by the Finsen lamp. Photography 
may therefore claim the discovery of these beneficial rays, 
which have proved victorious in many cases quite incur¬ 
able by other means. 

It will be evident that it was these rays of ultra-violet 
light which produced the portrait taken in total darkness, 
which was mentioned in the preceding chapter. 

In one of the Christmas lectures delivered at the Royal 
Institution of Great Britain in 1896, Professor Sylvanus 
Thompson made an interesting experiment which demon¬ 
strated the photographic action of these ultra-violet 
199 


MORE INVISIBLE RAYS 


rays. On a board there was a large sheet of apparently 
plain white paper. When the light of a powerful arc 
lamp was thrown upon the paper one could see nothing 
but an absolutely plain white paper. A photographer 
then set up his camera and took a photograph of the 
paper. The plate was immediately developed, whereupon 
it was seen that there was a bold inscription upon the 
apparently blank paper. This inscription was quite in¬ 
visible to the human eye, but not to the eye of the 
camera. The ordinary white light from the arc lamp was 
reflected by all parts of the white paper, and the eye 
therefore saw a plain sheet of white paper. The inscrip¬ 
tion, however, had been painted on in a colourless 
chemical liquid which absorbed the violet rays. This 
made no difference to the human eye, because these rays 
do not affect it in any case; the eye therefore does not 
miss them. The photographic plate misses these rays ; if 
they are absent, then the photographic action is not so 
great. Hence when the letters of the inscription failed 
to reflect these ultra-violet rays to the photographic 
plate, there would appear upon the plate a considerable 
want of chemical action at these places. In this way a 
record of the invisible inscription is obtained upon the 
photographic plate. 

The colourless liquid used for the foregoing experiment 
was sulphate of quinine dissolved in a solution of citric acid. 
The source of light was an electric arc lamp, which is very 
rich in ultra-violet light. 

The illustrations facing page 206, of the blood-stained 
handkerchief and the faded signature, may be explained 
in the same way. 


200 


MORE INVISIBLE RAYS 


So far we have been dealing, in this chapter, with the 
invisible rays of ordinary light. A beam of white light 
contains not only those different rates of ether vibration 
which produce the spectrum colours, but it also contains 
these invisible ultra-violet rays. While these rays, like 
the X-rays, affect a photographic plate, the properties of 
the two kinds of rays are different in several respects. We 
may demonstrate the most important difference by a 
simple experiment. We place the hand upon a photo¬ 
graphic plate and expose it to the action of ultra-violet 
rays. We merely obtain a uniform black shadow of the 
hand. Compare this with an X-ray photograph of the 
hand, and there is no comparison between the two results. 
The ultra-violet photograph is just the same as we could 
get by ordinary light if we laid some opaque object upon 
a negative during the exposure; the X-ray photograph 
I need not describe again. The ultra-violet rays will 
cause a fluorescent screen to shine, but only a solid shadow 
can be produced by the hand. The special photographic 
value of the X-rays lies in their penetrative power, and 
in the fact that different substances offer different resist¬ 
ances. 

When Professor Rdntgen made the important dis¬ 
covery that the X-rays affected a photographic plate, 
several experimenters set to work to find out if these rays, 
or other similar rays, could not be found in nature. 
Several scientific men turned their attention to phos¬ 
phorescent substances; there is a phosphorescent effect in 
an X-ray tube when at work. A phosphorescent sub¬ 
stance is one which, after being exposed to ordinary light, 


201 


MORE INVISIBLE RAYS 


will become luminous in the dark. The phosphorescent 
effect is, in some cases, merely momentary; in other sub¬ 
stances it lasts for many hours, or even for several days. 
Many of us have recollections of luminous match-boxes, 
etc., which were a marvel to our youthful minds. In the 
preceding chapter I had occasion to speak of fluorescent 
screens in connection with X-ray work. These screens 
only became luminous when the X-rays fell upon them; 
the effect disappeared with the withdrawal of the rays. 
The difference between fluorescence and phosphorescence 
will therefore be quite obvious. 

Experiments were made to see if phosphorescent sub¬ 
stances did not give off invisible rays along with the 
luminous rays. Of the different experiments, the most 
important was that of Professor Becquerel, of Paris. The 
salts of uranium were considered to be phosphorescent, 
although the resulting luminous effect was very short¬ 
lived. In order to find out if this substance might not 
possibly be giving off invisible rays, Becquerel exposed 
a piece of uranium salt to strong sunlight, allowing it to 
rest on the top of a light-proof envelope, which enclosed 
a photographic plate. When the plate was developed, 
there was no trace of sunlight, for the envelope was abso¬ 
lutely opaque to light; but rays had reached the plate 
from the uranium salts, and had formed the shadow of a 
metal cross, which had been laid beneath the uranium. It 
was quite certain that no luminous rays from the uranium 
had penetrated the envelope, so that the photographic 
action must have been the result of invisible rays emitted 
by the uranium salts. 

Then there comes a romantic incident, which reminds 


202 


MORE INVISIBLE RAYS 


one of Daguerre’s magic cupboard, of which we read 
in an earlier chapter. It so happened that on one 
occasion, when Becquerel was about to expose a piece of 
uranium salt to sunlight, with the object of making 
further photographic experiments, the sun disappeared 
behind the clouds. Becquerel put the uranium and the 
enclosed photographic plate in a drawer, intending to try 
the experiment later. We are then informed that Bec¬ 
querel coming one day and finding the uranium lying upon 
the envelope containing the photographic plate, the metal 
cross being again between the uranium and the plate, he 
somehow or other took the plate and developed it without 
subjecting the uranium to any exposure of light. He was 
very much surprised to find that the image of the cross 
again appeared upon this negative, even although the 
uranium had not been rendered phosphorescent by ex¬ 
posure to light. 

I have sometimes wondered if the thought of Daguerre’s 
magic cupboard came into Becquerel’s mind, when he 
opened the drawer and remembered his postponed experi¬ 
ment. He certainly had no reason to expect that an 
image would be formed upon the plate, seeing he had not 
exposed the uranium to sunlight. Be that as it may, this 
photographic plate has become of historical interest. It 
disclosed to Professor Becquerel the fact that the uranium 
was giving off* these invisible rays without having had an 
opportunity of bottling up the sunlight. 

Could it not be that the uranium had still retained 
some of the sunlight effect from a previous exposure ? 
This was not likely, as the phosphorescent effect of uranium 
is of very short duration. To make assurance doubly 


203 


MORE INVISIBLE RAYS 


sure, Becquercl took some uranium salts which he had 
chemically combined and crystallised in the dark. There 
could be no question of sunlight with these salts, as they 
had never seen the light. He then experimented with 
this virgin substance upon a photographic plate, and he 
found that there were invisible rays given off, just as 
energetic in their photographic action as were the rays of 
the earlier specimens which had been carefully exposed to 
sunlight. This was man’s first knowledge of radio-active 
bodies, and in honour of the discoverer these rays have 
been named Becquerel rays. 

It may seem to the reader as though this discovery 
was not of very much consequence in the workaday 
world. We cannot tell how far-reaching it may be. It 
led to Professor and Madame Curie’s discovery of radium. 
But what I want to point out at present is that photo¬ 
graphy was the means by which Professor Becquerel made 
this historical discovery of bodies emitting invisible radia¬ 
tions. Herein lay the discovery of a new property of 
matter—a property, the existence of which had remained 
sealed in nature’s book from all time, until revealed in 
1896 by Becquerel’s photographic plate. 

It is not within the province of our present subject to 
trace how the Curies, following up this pioneer experi¬ 
ment, discovered the much more radio-active substance 
which they christened radium. An electrical test was 
found which proved much more sensitive in detecting a 
radio-active substance than the photographic plate. Never¬ 
theless, it was the photographic plate which opened the 
door to this world of radio-activity. 

I remember seeing some of the negatives which had 
204 


MORE INVISIBLE RAYS 


been exposed to uranium in order to produce various 
skiagraphs. The reader would not reckon them of 
much value, merely judging them by their appearance. 
They will remain, however, of historic interest. The 
skiagraphs or radiographs produced by radium are 
more distinct, but they too fall far short of those pro¬ 
duced by Rontgen’s rays. Some interesting negatives 
have been obtained with radium, showing metal coins, 
keys, sleeve-links, etc. One experimenter, Soddy, adopted 
a very interesting plan. He placed some radium salts in 
a small test tube, and using it as a pencil, he traced the 
letters Ra, in imaginary writing, upon the black envelope 
enclosing a photographic plate. When the plate was 
developed the letters were clearly seen upon the negative. 
This experiment showed how very quickly the rays affected 
the photographic plate. 

The illustration facing page 196 is by far the best radium 
photograph I have yet seen. I am indebted to Mr. Edgar 
Senior, of the Battersea Polytechnic, for this interesting 
example. This experimenter has surprised photographers 
from time to time by his beautiful experiments. The 
method of taking this photograph was as follows. The 
object, a carved ivory needle-case, was placed in contact 
with a photographic plate, and a screen coated with a 
substance containing the radium was placed over it; the 
whole being contained in a box was kept in the dark. 
Although no visible radiation proceeded from the screen, 
the photograph was obtained on allowing some time to 
elapse before withdrawing the plate. 

It is a curious fact that luminous or phosphorescent 
paints, although losing their luminous effect after several 
205 


MORE INVISIBLE RAYS 


days at the most when withdrawn from exposure to light, 
will continue for many weeks to emit invisible rays which 
affect a photographic plate. 

The well-known incandescent gas mantle emits invisible 
rays. An unused mantle is cut up so that it will lie flat 
upon a black envelope containing a photographic plate. 
The plate and the mantle are then put aside in a dark 
drawer for eight days, and when developed it will be found 
that these invisible rays have photographed the texture of 
the mantle upon the negative. 

Many ordinary substances will similarly affect a photo¬ 
graphic plate, if the exposure be long enough; an 
exposure of several days may be required. A piece of 
polished zinc is a very active body, while the printer’s 
ink upon a five-pound note will photograph itself upon 
a photographic plate in the dark. I remember an 
amusing incident in this connection. Many years ago 
a friend received a boxful of photographic plates to 
develop for a friend of his. When the plates were 
developed, not only did some excellent photographs of 
interesting places appear, but an uninvited guest had 
also been at work. Across each picture there was a bold 
inscription printed. In the clear sky of one picture 
appeared the words “use so-and-so’s baking powder,” 
while on another stood an advertisement of soap, and so 
on. In packing up the plates, the sender had placed 
pieces of printed paper between them, and on the journey 
the printer’s ink had affected the still sensitive plates. 
These substances are not radio-active bodies; they will 
not respond to the electric test of altering the con¬ 
ductivity of air. Some physicists maintain that these 
206 



Py permission of 


Professor Reiss, Lausanne University 


Photographing the Invisible 


The upper illustration is a photograph 01 a portion or a handkerchief from which 
some blood-stains had been washed out with soap and water, so that they were quite 
invisible to the eye. The photograph reveals their presence. The lower illustration 
is a photograph of part of an old french document from which the signature had dis¬ 
appeared. The camera saw what the eye could not see. (See chap, xiii.) 





















































































































































MORE INVISIBLE RAYS 


bodies emit invisible rays which act upon the chemicals 
on a photographic plate, but others believe the action to 
be a purely chemical one. 

It was thought by some experimenters that glow-flies 
or fire-flies emitted invisible photographic rays which 
could penetrate a sheet of iron and then affect a photo¬ 
graphic plate. One experimenter in Japan was said to 
have proved this by shutting up one thousand fire-flies in 
a shallow box, and then exposing a photographic plate 
beneath a sheet of iron upon which the box rested. I 
am informed, however, that this statement was afterwards 
withdrawn; possibly some stray light affected the ex¬ 
perimental plate. 

Referring again, for a moment, to radio-active bodies, 
there is one other point which may be of interest to the 
reader. He may wonder if it is possible to make a body 
radio-active, or if it is only a natural property. We shall 
take a case in which the photographic plate gives us a 
reply. If an aluminium or copper wire be electrically 
charged, to a high negative potential, for some hours, it 
is found that the wire will affect a photographic plate, 
and that it retains this property for several hours after the 
charge has been withdrawn. It has been proved, in this 
case, that the surface of the wire becomes radio-active, 
because radio-active matter from the atmosphere has 
been deposited upon it. It is not possible to make a 
body radio-active, except in this sense. 

It does not concern us in our present subject to inquire 
how radio-activity has brought to man the new know¬ 
ledge of the disintegration of the atom. The chief point 
of interest for us at present is the way in which this new 
207 


MORE INVISIBLE RAYS 


knowledge originated. We see Becquerel examining a 
newly developed photographic plate, and finding upon it 
the faint shadow of a copper cross, which he had laid in 
the dark, between a piece of uranium and the black 
envelope enclosing the sensitive plate. Here, indeed, 
began a true romance in the world of science. 


208 


CHAPTER XIV 


PHOTOGRAPHING MICROBES, &c. 


Daguerreotypes through the microscope—How photographs are taken 
through the microscope—An invisible image—Photographing a 
spider’s foot— Some beautiful microscopic shells—Nothing left to 
the imagination—Interesting points in high magnification—A 
difficulty overcome — Microbes — What are bacteria ?— Photo¬ 
micrographs of metals. 

I N X-ray photography we have seen how it is possible 
to photograph things which are invisible to the eye, 
because they are enclosed within other substances 
which are opaque to light. In the present chapter we 
are going to consider the means of photographing bodies 
which are invisible to the eye because of their minute 
size. While these objects are far below the range of our 
vision, we can see them by means of powerful micro¬ 
scopes. And it is because we are able to photograph 
objects through the microscope that we can obtain 
pictures of things that are below our range of vision. 

The idea of photographing through a microscope is not 
new. In the days of the daguerreotype a few scientists 
took photographs through the microscope, but the really 
fine work of photo-micrography has all been done during 
the present generation. 

We may gain a great deal of interesting and useful 
knowledge by means of these photo-micrographs. One 
occasionally hears these pictures spoken of as micro- 
209 


o 


PHOTOGRAPHING MICROBES, &c. 


photographs, but that is an error. A micro-photograph 
is a very small photograph, such as we have seen in 
souvenir penholders. When these are viewed through a 
small magnifying glass fixed immediately in front of the 
photograph, one sees quite a good picture of some place 
of interest. 

A glance at the illustration on the opposite page will 
show the beautiful detail obtained in a photograph taken 
through a microscope. 

When one takes a photo-micrograph one merely uses 
the microscope as the lens of the camera. The camera 
is only a dark chamber in which to place the photo¬ 
graphic plate in the proper position to receive the image 
formed by the lenses of the microscope. In other words, 
we wish to take a photographic record of the image we 
see when looking through the microscope. 

When we speak of photographing a spider’s foot, a 
fly’s wing, and so on, it is not to be supposed by the 
novice that we merely catch a spider or a fly and place it 
under the microscope and camera. We must first of all 
mount the object carefully upon a microscopic slide, so 
that it is firmly fixed between the glass slide and a thin 
cover glass. This we do in order that we may get the 
object flat enough to be focussed. Even then we shall 
find that the thicker parts of a fly’s wing are somewhat 
out of focus when the flat surface of the wing is in perfect 
focus. 

Sometimes we find the microscopist taking photographs 
with a very long camera, or with several cameras coupled 
together, measuring many feet in length. This he does in 
order to get a large picture giving detail which could not 


210 



Photo by Arthur E. Smith, London 

A Spider’s Foot 


This photograph was taken through a microscope, as explained in the text. It is difficult 
to realize that all this detail is contained in the foot of such a tiny creature as a spider. 
(See chap, xiv.) 
























PHOTOGRAPHING MICROBES, &c. 

be properly seen in a smaller photograph. Some friends 
maintain that one can get as good results by simply en¬ 
larging a smaller photograph, but with many microscopic 
objects this is not the case. 

I have had many an argument with microscopists upon 
this question. I hold that it is unfair only to measure 
the object in the final photograph, which may happen 
to be an enlarged copy of a very low magnification, and 
state the actual number of diameters that it is greater 
than the original object. One ought to state that the 
picture is an enlargement of a certain magnification. If 
we turn to the photographs shown opposite page 284 we 
have there a clear proof that an enlargement of the smaller 
abbey would not have all the detail shown in the tele¬ 
photograph below. It is hardly fair to make a com¬ 
parison between the reproductions in the book, as the 
graining of the process screen might destroy some fine 
details in the smaller picture; but taking the original 
photographs I have examined them very carefully, using a 
powerful magnifying glass to the smaller picture, and 
there is a lot of detail in the larger photograph which 
does not exist in the smaller picture. To take one item 
only, one can see telegraph poles and wires to the left of 
the abbey in the tele-photograph, but there is not the 
faintest impression of these in the smaller image. No 
amount of enlargement would ever add these to the 
image of the smaller photograph. Hence my argument 
concerning the microscope holds good. 

The photo-micrographer has really two focussings to 
attend to. He first of all adjusts the focus of his micro¬ 
scope till he gets the image perfectly sharp. To do this 


21 I 


PHOTOGRAPHING MICROBES, &c. 


he removes the camera and focuses his microscope in the 
ordinary way. He then couples his camera to the micro¬ 
scope and focuses the image upon the glass screen of his 
camera. 

If one thinks of an ordinary spider with his long thin 
legs of seemingly simple construction, one does not expect 
to see much detail in the foot of so small a creature. Its 
foot is about the size of the dot at the end of this 
sentence, and if one had never used the microscope one 
would probably think that the spider’s foot was in the form 
of a single round dot. The illustration, facing page 210, 
shows how much detail is really contained in so small a 
space. There is no artist’s imagination to be allowed for 
here; the spider’s foot was simply mounted between 
two pieces of glass and then photographed through a 
microscope. The spider’s foot in the original photograph 
was 400 times longer and 400 times broader than the 
real object. The block-maker, however, has had to 
reduce the photograph from 10 inches by 8 inches to 
4| inches by inches in order to suit the page of this 
book. 

After examining the photograph of the spider’s foot 
we can better understand how the little creature is able 
to suspend herself on her almost invisible thread. The 
late Dr. Carpenter tells us that the spider uses these 
comb-like claws for cleansing purposes, and for the 
manipulation of the thread of her snare. The same 
lover of nature tells us that these little claws are so sensi¬ 
tive that “by resting them upon a trap-line of silk 
carried to her den, she can, by a veritable telegraphy, 
discover instantly, not only the fact that there is prey 


212 


PHOTOGRAPHING MICROBES, &c. 

upon her snare, but the exact spot in the web of the 
snare in which that prey is entangled.” This she can do 
when she is “ far beyond the reach of vision.” 

We pick up another microscopic slide, marked poly- 
cystinci , and we desire to take a photograph of this 
through the microscope. Nothing can be seen by 
ordinary vision except a number of very small specks 
below the cover-glass. These might be mistaken for 
dust or fine white sand. In the lower illustration oppo¬ 
site page 216 we see one of these slides of polycystina 
photographed full size. What a difference between the 
visible detail in this and that in the larger illustration 
above it! This large photo-micrograph only represents 
a very small fraction of the polycystina contained in the 
microscope slide shown beneath. We no longer see 
simple specks of matter. Each of the tiny specks is 
found to be a beautifully formed shell. And what is 
even more marvellous, each of these tiny fossil shells at 
one time contained a living creature. It seems almost in¬ 
credible that so much design can possibly be contained in 
so small a speck in nature. 

These polycystina are fossil shells, the homes of 
creatures which lived many ages ago. Do any of these 
tiny creatures still live upon the earth ? Yes! we find 
their living representatives near the surface of certain 
oceans, and they are named radiolaria , having little rays 
projecting from their shells. When these tiny crea¬ 
tures die their shells fall to the bottom of the ocean, 
and after long ages go to form hard rock. It is in these 
rocks that we now find the polycystina of radiolaria which 
lived long ages ago. 


213 


PHOTOGRAPHING MICROBES, &c. 

Photo-micrography provides us with a means of spread¬ 
ing knowledge concerning microscopic objects much better 
than can be done by direct microscopy itself. Every 
one is not the possessor of a microscope, but although 
one may never have looked through a microscope, one 
can understand a photo-micrograph. When an ordinary 
person knows that he is looking at an actual photo¬ 
graph, he feels confident that he is seeing nature really 
as she is. When we came across wood engravings 
of snow crystals in our school books, many of us, I 
doubt not, gave the artist credit for a rather lively 
imagination. These exquisite and intricate geometrical 
designs, labelled snow crystals, had doubtless been sug¬ 
gested to the artist by the snowflake. We too had 
sometimes seen wonderful configurations in the flames as 
we sat listlessly over the fire. When, however, we are 
shown an actual photo-micrograph of the crystals formed 
by breathing upon a window during frost, wfc feel we are 
on safe ground. We know that all that multitude of 
exquisite forms must really exist exactly as we see it in 
the photograph. I do not mean to suggest that the 
artist wilfully misrepresents a microscopical object; I am 
describing the possible appreciation of such drawing in 
young minds. In the case of photo-micrography there 
can be no personal equation to discount—no artist’s 
imaginative licence to allow for. 

Then, again, not only does photo-micrography ensure a 
faithful reproduction, but the artist Light will draw the 
most delicate lines and complex structures in a manner 
which the draughtsman’s pen could not accomplish. 
Again, what the skilled draughtsman would take 
214 


PHOTOGRAPHING MICROBES, &c. 

laborious hours and perhaps days to draw, the pencil of 
nature will draw in a few seconds if the magnification be 
low, or in a few minutes if the magnification be great. 
Allowing for the time required to arrange the camera, to 
develop the negative, and to print the paper photograph, 
the whole time is a mere fraction of the draughtsman's 
time. Besides all this, the man who cannot draw a straight 
line or shape a curve may produce an excellent picture 
of the most complex organism by means of photo-micro- 
graphy. 

There is an interesting point that arises in connection 
with high magnifications. We all know the meaning of 
the refraction of light; we have seen a stick placed at an 
angle in water, and we have noticed that the stick ap¬ 
peared to be very decidedly bent at the point where it 
entered the water. We are therefore aware that light is 
bent or refracted when passing from one substance to 
another, such as air and water. The same happens when 
light passes from glass to air, and so we may picture the 
rays of light being bent as they pass out through the 
cover-glass of a microscope slide into the air space between 
the slide and the lens of the microscope. Even although 
the cover-glass is made as thin as it is possible, some rays 
will be bent outwards so that they miss the small lens 
altogether, and therefore fail to enter the microscope. 
This means that the resulting image will not be so 
bright or so perfect as it would otherwise be. How 
can this difficulty be overcome? We certainly cannot 
hope to make a thinner cover-glass; already it is merely 
a wafer, the weight of which is hardly perceptible in the 
hand. We can, however, prevent the bending of the rays 
215 


PHOTOGRAPHING MICROBES, &c. 


of light if we supply the light with a uniform path. 
The bending is caused by the difference in density between 
the glass and the air. If we fill the intervening air space, 
between the microscope slide and the lens, with water or 
with cedar oil, then the light will have no change of 
density to pass through. It will suffer no refraction in 
passing from the glass to the water or oil, so that all the 
light will enter the microscope and produce a brighter 
image and a better photo-micrograph. When one sees in 
a price list of microscopes, water-immersion or oil-immersion 
lenses, the meaning will be quite clear. 

In our first illustration (p. 210) we have a demonstra¬ 
tion of how photo-micrography is of assistance in the 
study of insect life. Then in the illustration facing page 
216 we have an example of how the beauty of very minute 
organisms is revealed. We might add photograph after 
photograph, showing a whole world of marvels beyond 
the range of ordinary vision. 

There is one other field of photo-micrography with 
which I shall deal at some length, because it is doubtless 
the most marvellous of all, not from the artistic, but from 
the practical point of view. I refer to the photography 
of microbes. In the two illustrations, just referred to, 
we have photographs of very minute objects, which are 
not themselves invisible, although the beauty of their 
design is hidden until revealed by the microscope. In the 
present case we are going to deal with photographs of 
objects which are totally invisible to our eyes; far below 
the range of unaided vision. 

It is a natural question to ask what these microbes or 
bacteria really are. I have occasionally found people 
216 



Photo by Arthur E. Smith, London 

Photomicrograph 

The large illustration is a photograph, taken through a microscope, and shows a very small 
portion of the “white specks ” (polycystina) seen in the lower illustration, but magnified enor¬ 
mously. The lower photograph gives the actual size of the objects which were photographed 
by the microscope. (See chapter xiv.) 






















PHOTOGRAPHING MICROBES, &c. 

picturing microbes as some kind of very minute insects, 
so small, of course, that they cannot be seen, but yet 
endowed with a sort of instinct or volition, enabling 
them to leave one infected person and direct their attack 
against a second person who happened to offer some attrac¬ 
tion or predisposition. A glance at the photographs of 
microbes facing page 220 will dispel any stray idea of insect 
life. 

Scientists were not very sure at first what bacteria 
really were. It could not be decided whether these 
minute organisms belonged to the animal or the vegetable 
kingdom. Were they a low form of animal life, or were 
they simple vegetable life? There was a great deal of 
lively debate before these all-important little organisms 
were finally settled down in the domain of botany. What 
then is a microbe or bacterium ? It is a very minute 
vegetable organism; a microscopic fungus, classed along 
with moulds and yeast. The study of bacteriology has 
been of the very greatest benefit to mankind, and photo¬ 
micrography has played no small part in the advancement 
of this knowledge. 

It is not within our present province to describe how 
the bacteriologist cultivates bacteria in peptonised meat 
jelly, etc., for the purposes of examination. Nor, again, 
how he stains his specimens with aniline dyes to make 
the forms of the bacteria more visible. It will be of 
interest to the reader, however, to see exactly what some 
of those bacteria look like. I have selected four different 
kinds of bacteria which will be quite distinct from one 
another to the eye of the uninitiated, and at the same 
time will represent well-known diseases. 

217 


PHOTOGRAPHING MICROBES, &c. 


Looking at the illustrations (p. 220), we notice that 
in the lower right-hand photo-micrograph some of the 
bacteria have the appearance of drumsticks. This peculiar 
formation is found in the disease germ of lockjaw , or 
to give it its more scientific name, tetanus . When the 
bacteria are in the form of little straight rods, as shown 
in this illustration, they are called bacilli , the singular of 
which is bacillus. It is only at a certain stage in its life- 
history that the tetanus bacillus has this drumstick ap¬ 
pearance. 

As this photograph is magnified one thousand diameters, 
the real bacillus is only one-millionth of the area shown 
here. If these tiny organisms enter a surgical wound, they 
set up a series of changes in the tissue, and produce a 
virulent poison, which acts upon the nervous system, and 
causes those most distressing spasms and convulsions 
associated with lockjaw. 

The upper left-hand photograph shows the bacillus of 
diphtheria. The little rods are slightly curved, and they 
are much smaller than the tetanus bacillus. These bacilli 
of diphtheria may be seen congregated in clumps, or in 
pairs, or they may be single. It is to counteract these 
tiny organisms that the anti-toxin serum is injected. 

Our next photograph is of Asiatic cholera, and here 
the bacilli take the form of spiral threads. Sometimes 
one finds a complete letter S. To show how easily these 
minute disease germs may be carried from one place to 
another, I may refer to an epidemic which occurred in 
1892. At this date a severe epidemic of Asiatic cholera 
originated in India, and quickly spread throughout 
Afghanistan, to Russia in Asia, and westwards along 
218 


PHOTOGRAPHING MICROBES, &c. 

the route of the railway; this whole area being affected 
within the space of three weeks. Russian emigrants then 
carried the germs to Hamburg and Antwerp. 

Our last photograph is of special interest, and I am 
indebted to Dr. R. M. Buchanan, Bacteriologist to the 
City of Glasgow, for the trouble he has taken in securing 
a photograph suitable for reproducing here. The microbe 
here is of an oval or kidney shape. It belongs to a 
large class of microbes that are more or less round-shaped 
and called cocci. Each cell is called a coccus . This 
photograph is of the micro-organism of cerebro-spinal 
fever, more commonly called “ spotted fever.” The 
characteristic arrangement in pairs is well shown. The 
large group in the centre of the photograph is contained 
within a cell the outline and nucleus of which are scarcely 
visible. The larger bodies are blood corpuscles. 

All these photographs are made on the same scale. 
The magnification in the original photographs is one 
thousand diameters, but this has been reduced in repro¬ 
duction, in order to get the four photographs on to the 
one page. 

The bacteriologist is not only familiar with the shapes 
and forms of the different bacteria, he knows their 
actual measurements. The inch is, of course, much too 
large a unit to use, and so he takes as his unit the one 
twenty-five thousandth part of an inch. The cholera 
bacillus measures from one to two of these units in length, 
and about half a unit in thickness. While these figures 
will not convey much to the mind of the reader, they 
give the bacteriologist a real measurement by which he 
may compare the different bacteria. It is impossible for 
219 


PHOTOGRAPHING MICROBES, kc. 


the mind adequately to conceive the actual size of any 
bacterium. We cannot imagine the divisions of an inch 
marked off into twenty-five thousand equal parts ; even 
when divided into sixty-four parts each division looks 
very small. Of course, the bacteriologist is not really 
measuring with so fine a scale, for he does not measure the 
actual bacillus, but a very large magnified image of it. 
For instance, if his photo-micrograph is one thousand 
magnifications, and he finds that a bacillus in this photo¬ 
graph measures one twenty-fifth of an inch, then he 
knows that the bacillus is one thousand times smaller 
than its photograph, which means that it will only 
measure one twenty-five thousandth part of an inch in 
nature. 

The orthodox plan of stating the amount of magnifica¬ 
tion shown in a photograph is to say that it is fifty 
diameters or one thousand diameters. Some people, not 
accustomed to microscopy, express surprise when they are 
informed that a certain object in a photo-micrograph is 
only multiplied by fifty diameters; they would have guessed 
a far greater magnification. It must not be thought that 
an object increased by fifty diameters means that it is 
only fifty times as large as the original. It is fifty times 
as long and also fifty times as broad, so that it is really 
two thousand five hundred times larger (50x50 = 2500). 
An object magnified one thousand diameters is therefore 
one million times larger, and so on. It is much more 
convenient to state the number of diameters by which an 
object has been magnified. We adopt this plan in every¬ 
day conversation concerning common objects. We say 
that one object is twice as long or twice as broad as 


220 




DIPHTHERIA. 


ASIATIC CHOLERA. 



SPOTTED FEVER. 


LOCKJAW. 


By permission 


Dr. R. M. Buchanan, Bacteriologist 


Photographs of Microbes 


These four photomicrographs show different types of bacteria. These mmute organisms 
are far below the range of vision ; they have been photographed through a powerful 
microscope. (See chap, xiv.) 








PHOTOGRAPHING MICROBES, &c. 

another, without stopping to consider the increase in 
area. 

Sufficient has been said to show that, in this depart¬ 
ment, photo-micrography reveals a whole world of activity, 
existing in air, earth, and water, which must have remained 
unexplored but for the microscope. It is difficult to realise 
that these bacteria are so very intimately connected with 
us as they really are; they are in the food we eat, the 
air we breathe, and the clothes we wear. They are in 
our mouths and in our stomachs. We must not look 
upon all bacteria as our enemies; they occupy a very 
important place in nature. They have very aptly been 
called the scavengers of nature , for they break down dead 
animal and vegetable matter. They complete the cycle 
of life, the dead matter being transformed into substances 
which again go to build up the living. 

Referring to the bacteria known as disease germs, it is 
a natural thing to wonder what useful purpose these serve 
in our bodies. None whatever; they are harmful para¬ 
sites ; they are not fulfilling their proper sphere in nature. 
Just as dirt is simply matter in the wrong place, so disease 
is bacteria in the wrong place. 

We owe a debt of gratitude to the bacteriologists who 
have discovered and studied these minute fungi, and who 
have thereby given the medical world new weapons with 
which to battle against disease. The bacteriologists are 
still at work in their laboratories, not only determining 
the nature of diseases, but on the look-out for further 
knowledge. 

Many beautiful photo-micrographs have recently been 


221 


PHOTOGRAPHING MICROBES, &c. 


taken of metals, showing their forms of construction and 
crystallisation, but these are of more technical than 
general interest. The other branches of study taken up 
in this chapter will be sufficient to demonstrate the very 
wide field which has been opened up to the scientist by 
the application of photo-micrography. 


222 


CHAPTER XV 


PHOTOGRAPHING UNDER 
DIFFICULTIES 


Taking photographs in a coal mine—An eighteen-inch coal seam— 
Some experiments with flash-powder—The photographer baffled— 
Plenty of light — A more disappointing expedition — A third 
attempt — Another defeat — A new line of attack — A long 
exposure — Ultimate success—The patient miners — A unique 
photograph. 

W HEN one meets with totally new conditions 
in taking a photograph one feels puzzled to 
know how to act, what exposure to give. This 
was my position when I determined to go down a coal 
mine and try to photograph an electric coal-cutter in a 
very narrow seam, measuring only eighteen inches from 
floor to roof. Many photographs had been taken 
previously in coal mines, but in such cases the photo¬ 
grapher had a reasonable space to work in. My ambition 
was to photograph the coal-cutting machine, and the two 
miners controlling it, in their exact working positions. 
This I wanted as an illustration for The Romance of 
Modem Electricity. 

Inquiries as to the source of light to use were not very 
encouraging; photographers’ opinions were so widely 
different. However, I determined to try a powerful 
flash-powder, believing that I could not have too much 
223 


PHOTOGRAPHING 

light, when the whole surroundings were to be a dead 
black. 

I was fortunate in falling in with the manager of one 
of the largest concerns for manufacturing flash-powders. 
This gentleman supplied me with a very neat little inven¬ 
tion of his own, whereby the powder might be ignited 
without the risk of having one’s fingers burnt. This con¬ 
sisted of a small metal tray or saucer, supported upon an 
upright pillar passing through its centre. The tray could 
be slid up or down upon this pillar, and fixed in any 
desired position by means of a binding screw. The top 
of the pillar was made tubular, the hole being made just 
large enough to hold a wax match when folded in two. 
The method of igniting the powder was very simple. 
A wax match was doubled so that the plain end extended 
up above the match head. The plain end was then 
frayed out so that it could be easily ignited, without 
setting the head alight. 

The prepared match was first placed in the top of the 
pillar, and the desired amount of flash-powder placed in 
the tray. The powder was then heaped up, so that it 
just covered the head of the match, and left the plain end 
projecting upwards. A light was then applied to this 
frayed end of the match ; there was no fear of igniting 
the powder in this operation, as this powder could not be 
ignited by a naked light. When the buried head of the 
match, however, caught fire, its miniature explosion ignited 
the powder, and there was a sudden flash of very brilliant 
light. 

Having obtained permission to make photographic 
experiments in a large colliery where naked lights could 
224 


UNDER DIFFICULTIES 


be used with safety, I next secured the assistance of a 
friend who is an expert amateur photographer. 

It was necessary to carry out the photographic expedi¬ 
tion during the night, as the coal-cutters were not at work 
in the daytime. 

We set out by rail to the mining district, hopeful of 
securing an interesting photograph. The manager of the 
mine was very interested in our proposed experiments. 
He told us incidentally that several photographers had 
already tried the same subject, but had got no results. 
This was not very encouraging, yet we were hopeful that 
we were armed with a better source of light than our pre¬ 
decessors. 

The manager was very good in accompanying us down 
the pit. I had been down several pits on former occa¬ 
sions, but my friend had not been previously down a 
mine shaft, so he got instructions to take a firm hold on 
the cross-bar of the cage in which we were to be lowered 
into the bowels of the earth. It seemed quite a long 
downward journey, but we had still a long way to walk 
after reaching the bottom. At first we walked quite 
erect, but on turning off the main road we were forced to 
walk in a very crooked position, or we ran the risk of 
collision between our heads and the rugged roof. When 
we encountered a fall of the roof, which here and there 
almost blocked our way, we found the photographic 
apparatus an awkward burden. Sometimes one had prac¬ 
tically to crawl through a hole. At last we entered a 
very small road or passage, in which the roof was so low 
that one even knocked one’s back against it when walking 
along with the body bent in the form of a right angle. 
225 


P 


PHOTOGRAPHING 


It was a genuine relief when the manager informed us that 
we had reached the end of our journey. We sat down to 
try and straighten out our bent backs. 

This little narrow, low-roofed passage in which we were 
now sitting seemed to come to a dead end. The manager, 
however, was able to show us with the aid of his lamp 
that a very shallow passage ran past the end of our road. 
The roof close overhead dipped right down in front of us 
to within eighteen inches of the ground, and at this 
point we tapped the shallow passage. It was only a few 
feet in width, but it extended several hundred feet in 
length, while it was only eighteen inches from floor to 
roof. It was practically like a great big crack in the solid 
earth, and yet two miners were to work all night in this 
confined space and look after a powerful coal-cutting 
machine. 

As the machine practically filled up the whole space 
from floor to roof, our only chance of photographing it 
would be as it passed the end of our road. I crawled 
into the eighteen-inch seam a little way, till I could hear 
the hum of the coal-cutter in the distance. I was quite 
glad to crawl back again; it is an eerie feeling to be in 
such a small space, far down in the earth, when one is not 
accustomed to it. We then set about preparing the 
camera and the flash-powder. The photographer had 
brought with him a regulation stand for the camera, but 
the only stand suitable to the circumstances was a small 
block of wood to raise the camera a few inches off* the 
ground. We then placed a miner’s lamp in the narrow 
passage along which the machine was to pass, and focussed 
as best we could by this light. Water had condensed upon 
226 


UNDER DIFFICULTIES 


the camera lenses, but this had evaporated before the 
machine came along. 

When the machine arrived, we were disappointed to 
find that it more than filled up the end of our road, 
but it did not come up to the face of our opening. It 
was several feet within the low passage, and this meant 
that our light must be able to penetrate this low, dark 
passage for several feet. Picture the photographer sitting 
upon the floor, with a dark hole extending in front of 
him, the height of the hole being no greater than the 
space between an ordinary chair seat and the floor of a 
room. He is going to try and photograph a machine 
and two miners lying several feet within this low-roofed 
hole. Our hopes could only be sustained with some 
effort. 

Extinguishing all the miners 1 lights and leaving the 
lens of the camera open, I set a light to the frayed end of 
the match in the powder tray. A moment of waiting, 
and then there was a sudden blinding flash of light. 
What an intense light! Surely we had secured a good 
picture ! But remembering the reported failures of those 
who had already tried the same subject, we made several 
further attempts, each time increasing the amount of 
flash-powder. For the final attempt I warned all the 
men to close their eyes; even then the light was quite 
blinding, and one had the impression of light which 
seemed to last for many seconds. Between each ignition 
we had to take off* our coats and use them as fans to 
drive the smoke out of the passage. The manager told 
us that we had certainly succeeded in producing a far 
brighter light than any of our predecessors had. We 
227 


PHOTOGRAPHING 


went off hopeful that when our plates were developed we 
should find that we had obtained good results. But 
development of the plates blasted our hopes. We had 
only secured a photograph of the ground immediately in 
front of the camera; our light had altogether failed to 
penetrate the lower passage. 

From the appearance of the negatives we thought it 
possible that the flame had shot along the low roof and 
got in front of the lens. Our own passage was so low 
that when sitting upon the ground beside the camera our 
heads were just touching the roof, and by stretching out 
our arms we could touch the walls of the passage on either 
side. 

There was nothing for it but to try again, with the 
flash-light farther back behind the camera, and so we 
arranged for a second expedition. On this occasion I 
had intended trying the effect of the flash-powder in one 
of the main roads where we had more room. I got a 
miner to crawl into a narrow seam, the end of which 
happened to meet the main road. We set the camera 
and prepared the flash-powder, but the powder refused to 
go off. One match after another was tried; the powder 
remained cold and indifferent. Coax it as we would, it would 
not respond, and so we came to the conclusion that the 
constituents of the powder must have been incorrectly 
mixed. This was decidedly disappointing after having 
travelled so far and having made all the necessary pre¬ 
parations. 

The following day I made an experiment with the same 
powder and found that it ignited all right. It therefore 
occurred to me that it must have been the matches that 
228 


UNDER DIFFICULTIES 


were at fault. I then remembered that I had purchased 
the matches from a street-vendor on the way to the 
railway station. A simple examination proved the 
matches to be of foreign origin ; the wax part was largely 
composed of wood, and the flame of the head was very 
poor. Hie explosion of the head was not sufficient to 
ignite the powder. 

A third expedition was therefore called for, and on this 
occasion we went armed with several kinds of flash-powder 
and a liberal supply of British-made wax vestas. We 
first of all carried out the experiment in the main road 
which we had intended trying on the last visit. In this 
case the miner was several feet within the eighteen-inch 
seam, but we were in the main road, where we had plenty 
of air space for the flash-light. Having snapped a few 
photographs in this position, we proceeded to the place 
where one of the coal-cutting machines was at work. 
Here we exposed several plates, varying the amount of 
flash-powder at each exposure, and taking good care that 
the flame could not shoot out in front of the camera. 
Upon developing these plates the following evening, we 
found that we had secured a good photograph of the 
miner in the narrow seam off* the main road; but those 
of the machine taken from the narrow passage were 
worthless. A reproduction of the main-road photograph 
is shown in the upper illustration facing page 230. This, 
however, was not what we aimed at. It was quite evident 
that we could never take the photograph of the machine 
from the narrow passage, because of the confined space in 
which to set off the flash-powder. 

It then occurred to me to try acetylene gas. I called 
229 


PHOTOGRAPHING 


upon the manager of the business selling flash-powder 
and reported the results of my experiments. He quite 
agreed that there was no use in making any further 
attempt with powder. He too thought that acetylene 
gas was my only remaining hope, and he very kindly 
offered to lend me a large portable acetylene gas apparatus, 
a gasometer for four burners. He further volunteered to 
accompany me on this fourth expedition. As this gentle¬ 
man was exceptionally tall, I tried to dissuade him; one 
of ordinary height finds it trying enough to crawl along 
the low, narrow passages. However, my friend was willing 
to take all risk; he had become interested in my diffi¬ 
culties and in my determination not to be beaten. 

In order to do all that could be done on this trip, 
which was to be the final one, whether successful or not, 
I decided to make some preliminary experiments in the 
mine before the machine reached our road. I therefore 
made up a box with developing trays, all necessary chemi¬ 
cals, and a dark lamp. This would enable us to make 
some trial exposures and develop them in the mine before 
the machine reached us, so that we might act with some 
confidence when the machine did arrive. 

Our burdens on this occasion were very considerably 
increased. In addition to the camera case, we had the 
bulky gasometer and its accompanying apparatus, while 
the box of chemicals was a rather awkward load. When 
we arrived at the mines, the manager said he had never 
met such persistent folk before; but I assured him that 
we too would acknowledge our defeat if we were beaten 
on this occasion. 

It was most unfortunate that this night there had been 
230 



Down in a Coal-mine 

In the upper illustration the miner was lying in a narrow working, while the camera 
was in the main road. This photograph was taken with a flash-light. It was impossible 
to take the lower photograph by such means ; the coal-cutting machine and the two 
men were several feet within a working measuring only eighteen inches from floor to roof. 
(See chap, xv.) 




















































* 






























UNDER DIFFICULTIES 


some bad falls of the roof in the direct road, which we 
had travelled on the three former occasions. This 
necessitated our going down another shaft and approach¬ 
ing the coal-cutter by a much longer route. Here we 
were with all our additional burdens. I was truly sorry 
for my tall friend. Even with my previous experience, I 
found it a most trying ordeal. Several times I slipped 
upon a clay soil, and my box of precious chemicals nearly 
came to grief. We stumbled along as best we could, 
willingly accepting a bruised arm more than once, in order 
to save the apparatus. There seemed to be no end to this 
journey, and when we did reach the eighteen-inch seam, 
my friend said he really thought he could never manage 
to get out again. When we cooled down, our spirits 
revived, and we set about making a trial picture, to test 
the necessary duration of exposure. 

We got one of the miners to lie along, in the narrow 
seam, in the position which the machine would occupy 
later. We then charged the acetylene apparatus and set 
the four burners alight. We tried one exposure of two 
minutes and another of five minutes. All lights were 
then extinguished, while I developed these two plates. 
The first was under-exposed, and the second one seemed to 
be about right. We prepared for the approach of the 
coal-cutter, as we heard it drawing nearer. Suddenly its 
business-like hum ceased ; there had been a mishap to the 
machinery. It took the two machine men some time to 
get matters put right. Imagine working with the heavy 
parts of a machine, while lying on one’s side in a space no 
higher than beneath an ordinary chair-seat! 

When the machine at last came into position, I told 


231 


PHOTOGRAPHING 


the two men that I was sorry to find it would be necessary 
for them to remain perfectly still for five minutes, and 
that the same five minutes would seem to them to be 
more like a quarter of an hour. 

Time, with all its celerity, moves slowly on to those 
whose whole employment is to watch its flight. 

Johnson. 

The coal-cutting machine practically filled up the 
opening to the seam, so that the two men could just show 
their faces—one at either end of the machine. It was no 
easy task to remain still for five minutes, and especially 
so with four blinding lights reflected full on to their faces. 
To make matters worse, an accident happened to the 
acetylene apparatus, the light suddenly went out, but 
shouting to the men to remain in the same position, we 
soon had the lights on again. Because of this mishap we 
thought it better to increase the time of exposure slightly, 
so that these miners had fully six minutes to remain 
motionless. How very ably they performed their task is 
witnessed by the lower illustration facing page 230, which 
is a direct reproduction of the photograph taken under 
these trying circumstances. 

It will be understood that only the trial plates were 
developed in the mine. The negative from which the 
illustration has been made was developed above ground. 
Those who are engaged in practical photography will 
understand that this was not a simple case of throwing the 
developer upon the plate, fixing, washing and drying it, 
and then printing it on paper. The plate required a great 
deal of careful manipulation during the developing pro¬ 
cess. Fortunately my friend was a clever chemist, and 
232 


UNDER DIFFICULTIES 


knew exactly the right thing to do. The image was then 
transferred from one plate to another several times. One 
object in this was to equalise the light over the picture, 
and to this end the negative was placed at a certain angle 
to a powerful light at each exposure. 

Many good photographs have been taken in coal mines, 
and without all this trouble; but, as far as I know, there 
has been no other picture taken in so narrow a seam. It 
was the limit of space which made the task so difficult. 
A friend has informed me that he saw a similar photo¬ 
graph shown in an electrical engineer’s business book. The 
photograph he referred to was not only similar, it was the 
same; permission having been granted to reproduce my 
picture. 


233 


CHAPTER XVI 


TELEGRAPHING PHOTOGRAPHS 

An amusing story—All that the electric current can do—An early 
patent—Professor Korn’s invention—The peculiar property of 
selenium—A simple analogy—The transmitting instrument—How 
it works—The receiving instrument—Its operation—Transmission 
of a photograph described—Utility of the invention—The speed 
at which it works. 

W E speak of telegraphing money to a friend ; but 
I hardly think, however green a country youth 
may be, that he will picture actual coin passing 
between one place and another by means of the tele¬ 
graphic wire. Some of us may have heard the story of 
a countryman who, in the early days of the telegraph, 
bought a pair of boots for his wife, and thinking to send 
them immediately to her, he threw them into the air so 
that they fell astride a telegraph wire. Even the greenest 
of country cousins could not be credited with such sim¬ 
plicity to-day. How then are we going to send a photo¬ 
graph by means of the telegraph wire P 

It is a simple matter telegraphing money. We pay 
the cash to the nearest postal telegraph office, and the 
officials transmit the intelligence, by ordinary telegraph, 
that a certain sum of money has been paid by the sender, 
and that a like sum is to be paid at the distant town to 
Mr. So-and-So. If you were to hand in a photograph 

234 


TELEGRAPHING PHOTOGRAPHS 


and ask the postal authorities to transmit it to a certain 
distant friend, the case would be quite different. There 
is no saying but some day we may find the Postal Guides 
giving a rate of charges for transmitting photographs by 
telegraph. In any case, the actual transmission of photo¬ 
graphs has been accomplished. 

All that the telegraph can really transmit is electric 
currents. »'We must therefore control these currents by 
a photograph, and then cause these currents to reproduce 
the photograph at the distant end of the telegraph line. 
Even when we transmit speech by the electric telephone, 
we have only electric currents passing between the sender 
and the receiver. The vibrations of sound control the 
outgoing electric current, and the incoming current sets 
up corresponding vibrations and thus reproduces the 
original sound. But how is a photograph to be converted 
into electric currents ? 

One of the earliest patents taken out in America in 
this connection suggests a mechanical plan of reading the 
photograph. An impression of the photograph is taken 
on a gelatine surface, and then mounted on a drum or 
cylinder such as is used in the phonograph. Indeed, the 
whole idea is very similar to the idea of the phonograph. 
When the drum is revolved a needle rises and falls accord¬ 
ing to the relief and depression of the photo-gelatine 
surface, and the movements of this little needle control 
an electric current passing out to the distant telegraph 
station. The reproduction at the other end is purely 
mechanical. There is a needle point, which is set in 
motion by the electric current, so that it rises and falls 
in exact sympathy with the needle at the sending end. 

235 


TELEGRAPHING PHOTOGRAPHS 


This needle rests upon a plain wax cylinder, which re¬ 
volves in synchrony with the sending drum. The needle 
therefore cuts depressions of varying depths as the wax 
surface passes under it. In this way a reproduction is 
made of the photo-relief gelatine surface at the sending 
end.; I have seen prints of these early experiments, and 
while they were good, considering the mechanical means 
of reproduction, no one could call them facsimiles of the 
originals. 

Professor Korn, of Munich University, has recently in¬ 
vented a much more perfect method. It is an instrument 
which uses a 'pencil of light instead of a cutting stylo, and 
can therefore do much finer work. 

In order that the reader may clearly understand the 
action of Professor Korn’s invention, he must first of all 
be able to appreciate the peculiar property possessed by a 
somewhat rare substance known as selenium. This is a 
non-metallic element which comes under the same cate¬ 
gory as sulphur. Selenium has a strange and almost 
magic property. Its resistance to the passage of an 
electric current through it varies according to the amount 
of light falling upon it. We can adjust matters so that 
in the dark no current will pass through it, but as soon 
as some light falls upon it, the electric current is able 
to cross it, and the more light, the more current 
passes. 

Picture the selenium as being analogous to an electric 
bell push. A wire comes from the battery to the push, 
and another wire leads away from the push to the electric 
bell, and from there back to the battery. The circuit is 
complete, except that the push forms a break in the 
236 


TELEGRAPHING PHOTOGRAPHS 


circuit. When the push is pressed, then the break is 
bridged over and a path is provided for the current to 
get from the batter^ to the bell. When the button of 
the push is released the circuit is again broken and the 
ringing of the bell ceases. Just so with selenium. When 
placed in the dark it is analogous to the push with the 
circuit normally broken, but when light falls upon the 
selenium the circuit is bridged and the bell rings. When 
the light is withdrawn it is analogous to releasing the 
push and thereby breaking the circuit once more. 

Our analogy does not carry us far enough. In the case 
of the bell push, it makes no difference whether the push 
is closed by a child of five years or a powerful man of 
fifty years of age. The selenium, however, takes very 
particular notice of the power of the light operating 
it. If only a feeble light falls upon it, then the electric 
resistance of the selenium is only slightly reduced and a 
feeble electric current is allowed to pass. A powerful 
light breaks down the resistance of the selenium and 
permits a stronger current to pass. It is just as though 
the light withdrew a barrier from the path of the electric 
current, opening the barrier wider and wider as the light 
increases, and closing it again according to any reduction 
in the light. I have endeavoured to make this action 
of the selenium somewhat picturesque, as it is a peculiar 
property such as we do not meet with in everyday 
life. 

We are now in a position to picture a selenium “push” 
or cell, through which the battery current must pass on 
its way to the telegraph line. This selenium cell is 
placed within a large dark cylinder in which there is only 

237 


TELEGRAPHING PHOTOGRAPHS 


a small aperture. An electric lamp is so arranged that 
its light is focussed upon the small hole in the protecting 
cylinder. A pencil of light will therefore pass through 
and fall upon the selenium within. The selenium will 
at once become conductive, and will allow the battery 
current to pass out to the telegraph line. A constant 
light would give a constant current on the line, but we 
wish to control the light reaching the selenium and make 
it interpret the photograph. We therefore mount a 
transparency of the photograph upon a glass drum, 
which also surrounds the sensitive selenium. If a black 
part of the photograph happens to come between the 
pencil of light and the selenium, then all light will be cut 
off from the selenium and no electric current will be 
able to pass out from the battery to the line wire. If 
we can pass each part of the photograph in succession 
beneath the pencil of light, then we shall have the 
selenium’s resistance constantly altering in accordance 
with the light and shade in the photograph, and the 
selenium in turn will cause an increasing and decreasing 
electric current to pass out from the battery to the 
distant telegraph station. A dark patch on the photo¬ 
graph will be represented by no current. A light patch, 
being transparent, will allow a lot of light to strike the 
selenium, so that the white parts of the photograph will 
be represented by the full electric current. Between the 
dark and the transparent parts of the picture there will 
be a great variety of shade. The more opaque these 
parts are, the less light will pass through to the selenium, 
and consequently the weaker will the electric current be. 

It only remains to arrange that the whole of the 
238 


TELEGRAPHING PHOTOGRAPHS 

photograph will be read by the pencil of light. The 
phonograph cylinder with its wax record gives us 
the exact motion required, but as it will not be con¬ 
venient to move the pencil of light along the length of 
the cylinder, we must make the cylinder itself, with its 
surrounding photograph, move along from right to left, 
while it also revolves. In this way every part of the 
picture is brought in succession under the active pencil of 
light. We therefore have an electric current passing out 
to the telegraph line, and the variations in this current 
will exactly correspond with the variations of light and 
shade in the photograph. 

Before watching the transmission of a photograph we 
had better pay a flying visit to the distant telegraph 
station and see how the varying electric current is to be 
translated again into light and shade. There we have an 
arrangement very similar in its general appearance to the 
transmitting instrument. We have a dark protecting 
cylinder with a small aperture through which a pencil of 
light may pass. In this receiving instrument the pencil 
of light is controlled by a small aluminium shutter. 
This little shutter, in its normal position, completely 
blocks the passage of the light. If the shutter is turned 
very slightly on its axis, it allows a little light to pass into 
the cylinder. The further the shutter is turned the more 
light passes, until it is full open, when the whole light 
passes into the cylinder. Inside the protecting cylinder 
is a drum carrying a sensitised photographic film; the 
movement of this drum is identical with the movement of 
the transmitter’s drum. 

The pencil of light falling upon the photographic film 

239 


TELEGRAPHING PHOTOGRAPHS 


will affect it just as an ordinary photographic plate is 
affected in the camera. In the ordinary camera the whole 
plate is acted upon at one time by the light and dark 
image falling upon it. In this photo-telegraphic 1 ap¬ 
paratus the picture is gradually built up by the pencil of 
light travelling across the photographic film in successive 
lines. 

It only remains to control the movement of the little 
aluminium shutter, the position of which determines the 
strength of the pencil of light falling upon the sensitised 
surface. The little shutter is turned bv the electric cur¬ 
rent coming in from the distant transmitter. Some 
readers may be curious to learn how this turning of the 
shutter is accomplished. Those who have read The 
Romance of Modem Electricity , which has already ap¬ 
peared in this series, will remember that when an electric 
current passes through a coil of wire placed between the 
poles of a magnet, the coil, if free, will turn round and 
seek to set itself at right angles to the plane of the 
magnet. If the current be only a weak one the coil may 
be arranged so that it will only be turned a very little by 
such a current, but as the current is increased the coil is 
turned further. In Professor Korn's receiving instrument 
a simple coil of copper wire has the little aluminium 
shutter attached to it. It is so placed that when the 
coil is turned by the electric current the little shutter acts 
towards the pencil of light just as a water-tap acts 

1 Professor Korn calls his pictures tele-photographs, but as we 
already use this word in connection with photographs taken by means 
of a tele-photo lens, it might be better to call Professor Korn’s pic¬ 
tures photo-telegrams, or at least to speak of his process as being 
photo-telegraphic. 


240 



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TELEGRAPHING PHOTOGRAPHS 


towards the water. The further this little shutter is 
turned the more light is permitted to pass. 

If no current comes in from the distant station, the 
shutter will remain in its normal position and thus pre¬ 
vent any light from falling upon the photographic 
film. The strength of the electric current sent out by 
the transmitter will determine the amount of light 
which the shutter will allow to pass into the protecting 
cylinder. 

In this simple manner the variations of the incoming 
electric current are translated into variations in the 
strength of the pencil of light. The revolving photo¬ 
graphic film upon which this pencil of light falls records 
all the variations of light and shade. The photographic 
record will not be visible until the film has been chemic¬ 
ally developed, but in describing the transmission of a 
photograph I shall suppose, for the sake of simplicity, 
that the image is immediately visible. 

As our demonstration is only to be in imagination we 
can be in two places at once, so that we may watch both 
the transmitting and the receiving apparatus, which are 
placed in two towns separated by hundreds of miles. 
Everything is in readiness, and the two cylinders, one at 
either station, are set revolving at the same time. It is 
necessary that the cylinders move in exact sympathy or 
synchrony, and there is a special arrangement to ensure 
this. The photograph we are about to transmit is one of 
the Crown Prince of Germany, as shown in the left- 
hand illustration facing page 240. 

The pencil of light in the transmitter first falls upon 
the grey background, which permits a certain amount of 
Q 241 


TELEGRAPHING PHOTOGRAPHS 


light to pass through it and affect the enclosed selenium. 
A corresponding electric current is allowed to pass out to 
the distant station, where the little shutter, under the 
influence of this electric current, is turned slightly round, 
so that a faint pencil of light is allowed to pass and fall 
upon the photographic film. This leaves a record of 
medium activity, or grey, upon the developed film. This 
condition of things continues until the hat in the photo¬ 
graph comes under the pencil of light. Here a stronger 
light at once reaches the selenium, a more powerful 
electric current reaches the distant station, and the 
shutter, turning still further round, permits a stronger 
pencil of light to fall upon the photographic film, causing 
it to become black. Then when the transmitting pencil 
of light falls upon the black ribbon band of the hat, 
almost all light is cut off* from the selenium; practically 
no electric current reaches the distant station, so that the 
little shutter is left to block the way of the pencil of 
light in the receiver. The photographic film will remain 
unaffected, and therefore transparent on the negative. 
And so on and so on, until the whole of the photograph 
has passed beneath the transmitting pencil of light and 
been reproduced as a negative at the distant station. 
This negative may then be used to print off any number 
of positives desired. There is necessarily a slightly 
lined appearance in the reproduced photograph, but from 
a little distance this is not seen, and, indeed, it does not 
interfere in any way with the portrait. 

From this somewhat crude description it will be seen 
that all the variations of light and shade in the original 
photograph may be reproduced at a far distant station. 

242 


TELEGRAPHING PHOTOGRAPHS 


Photographs have been transmitted by Professor Korn’s 
apparatus over a distance of many hundreds of miles. 

It is not at all likely that we shall in the future be 
continually telegraphing our photographs to our distant 
friends, but there are many useful purposes to which this 
invention may be put. The police authorities may have 
occasion to telegraph the photograph of a criminal from 
one city to another for the purposes of identification. Plow 
much more helpful than a mere word description ! Then 
the pictorial papers may have photographs of important 
events immediately telegraphed from long distances. 

It is obvious that the speed at which such photographs 
may be transmitted will not be dependent upon the 
celerity of the electric current, for it is at its destination 
“ in less than no time.” The speed of the transmission 
of a photograph will depend upon the sensitiveness of 
the selenium cell, and also upon the rapidity with which 
the shutter in the receiver may be operated. Complete 
photographs have already been sent in the space of ten 
minutes. 

The right-hand illustration opposite page 240 is a 
photograph of the inventor himself as it was reproduced 
by the electric telegraph at a distant station. 

A technical description of this photo-telegraphic apparatus is 
given by the author in the journal Electricity (London), Vol. XXI, 
Nos. 23, 24, and 25, 1907. 


243 


CHAPTER XVII 


NATURE’S CAMERA 


The eye compared with the camera—How Nature protects her camera 
—The iris and the iris diaphragm—The inverted image—Why do 
we not see things upside down?—The true function of Nature’s 
camera—Thousands of images formed by the eye of a beetle—A 
shadow cast upon the retina appears to be upside down—An in¬ 
teresting experiment—Why the image in the camera is inverted— 
The bending of light demonstrated—The camera lucida again— 
Photographic action of the retina—John Dalton’s colour-blindness 
—Interesting colour experiments with the eye—Why we have two 
eyes—The stereoscope. 


W E may admire the very excellent workmanship 
in the modern camera; the beautiful images 
it produces; the wonderful amount of light 
it lays hold of, so that it can snap the image of a 
flying train. Yet all sinks into insignificance when we 
once realise the beauty of Nature's camera. The modern 
camera looks quite like a rough copy of the construction 
of the human eye. 

In Nature’s camera we have the dark chamber, the lens 
for focussing, the iris diaphragm, which opens and closes, 
and we have the sensitive or sensitised screen with an 
image produced upon it. 

In a camera we must either move the lens or the focus¬ 
ing screen to and fro, in order to bring the image to a 
focus. An opera glass, a telescope, a microscope, a magic 
lantern, have all similar arrangements for altering the 

244 


NATURE’S CAMERA 


relative positions of the lenses. Nature’s camera far sur¬ 
passes all such devices. It would not be convenient to 
move the back of the eye to and fro, or to give the lens 
a similar motion, so the lens alters its curvature to suit 
the necessary focus. If we are looking at an object very 
near at hand, the crystalline lens becomes more convex, 
especially the front; or, in simpler language, it bulges out. 
If viewing a distant object, the lens becomes flatter. 
This accommodation is obtained by the combined action 
of a circular ligament which holds the lens in position 
and a circular muscle attached to the capsule surrounding 
the lens. We may picture the crystalline lens as being 
made of a transparent jelly-like substance which is highly 
elastic. 

It may be helpful to take a look at the model of the 
eye illustrated opposite page 248. The first photograph 
shows the complete eyeball. This delicate camera of Nature 
is well protected in the bony eye-socket, which is lined with 
fat, so that the eyeball may be protected and easily moved. 
The movements of the eyeball are controlled by six muscles 
attached to it, and it is any irregularity in these muscles 
or in their movements which causes squinting. The ends 
of some of these muscles may be seen on the model. 

The eyeball is further protected by the eyelid and also 
by the eyelashes. The latter assist to prevent dust falling 
upon the eye, while the eyelids in conjunction with the 
tear-ducts keep the exposed part of the eye moist and 
clean. The eyebrows protect the eyes against the possi¬ 
bility of perspiration trickling down from the forehead. 

The eye has a still further protection. The eyelids are 
lined with a soft mucous membrane, and this not only 
245 


NATURE’S CAMERA 


lines the eyelids, but it comes from the upper eyelid right 
over the exposed part of the eyeball and joins the lower 
eyelid. This skin is known as the conjunctiva and serves 
as a sensitive protective covering to the eyeball. 

The white substance forming the outer coating of the 
eyeball is quite opaque to light, and is called the sclerotic . 
It forms the body of the camera. 

Under the white coat is another coating which is 
largely composed of blood-vessels. The space between 
these vessels is filled with cells containing granules of 
very dark brown or almost black pigment. This dark 
lining absorbs all the light which falls upon it, so that 
there will be no reflection inside the dark chamber. This 
second coat is called the choroid , and is analogous to the 
black lining of the camera. If this black lining com¬ 
pletely surrounded the interior of the eyeball, no light 
could enter. But in front of the crystalline lens it forms 
a curtain with a window or aperture in it. This curtain, 
which opens and closes, is called the iris, and the aper¬ 
ture or space at its centre is called the pupil. It will be 
observed that the pupil is not a material thing; it is 
merely the hole in the iris curtain. If we only possessed 
the pupils of our eyes, we should be in the same predica¬ 
ment as the Irishman, already referred to, who declared 
he had nothing left in his wardrobe but the armhole of 
an old waistcoat. 

It is the iris which gives colour to the eye, and the 
colour is simply dependent upon the amount of dark pig¬ 
ment interlining the iris. As it contains less or more 
pigment, the eye appears blue, grey, brown, or black. 

While the iris diaphragm in a modern camera is a 
246 


NATURE’S CAMERA 


rough imitation of the human iris, the purpose it serves 
is not the same. In Nature’s camera the iris regulates the 
amount of light which is to enter the eye; in a dull light 
we require more of it to stimulate the nervous system 
of the eye. If a strong light falls upon the eye, the 
pupil automatically becomes smaller. The involuntary 
motion of the iris is therefore to regulate the amount of 
light entering the eye. The iris diaphragm in the modern 
camera certainly regulates the amount of light entering 
the camera too, but that is not its object. The purpose 
of “ stopping down ” the camera lens is to get as sharp an 
image as possible. If the photographer opens the iris 
diaphragm to its full extent, he gets the maximum of 
light. This is an advantage, but some of the light is 
passing through the outer part of the lens, which does not 
focus the rays of light so perfectly as the central part of 
the lens does. The photographer’s object is therefore 
to use only that part of the lens which gives the most 
perfect image. Having cut off so much of the light, he 
has to give a much longer exposure. 

The operation of the iris in Nature’s camera is very 
beautiful. The closing of the iris is somewhat similar to 
the method adopted in a lady’s work-bag, in which a 
cord is pulled to close the top. In the iris there is a little 
circular band of muscle fibre, near the margin of the 
pupil, and when this contracts it closes the aperture. 
Some other muscle fibres, placed in the iris like spokes in 
a wheel, are capable of contracting and thus drawing the 
curtain open. The action of the iris may be observed by 
looking at one’s eyes in a mirror, and at the same time 
moving a lighted taper nearer to and farther from the eyes. 

247 


NATURES CAMERA 


The photographer takes great care of his lenses, pro¬ 
tecting them against possible injury. What does Nature 
do for her camera P The crystalline lens is immediately 
behind the open window of the iris, and it would not do 
to leave the little lens unprotected. There is a pro¬ 
tecting body called the cornea. It is just like a trans¬ 
parent window set in the white sclerotic coat. It is of 
necessity transparent, and is built up of layers, some¬ 
what after the fashion of an onion’s construction. The 
space between this cornea and the iris is filled with a 
watery fluid, known as the aqueous humour. 

Looking at the right-hand illustration on the opposite 
page, the iris with its protecting cornea is seen leaning 
against the base to the left-hand side. Close to this, lean¬ 
ing against the centre of the base, is the crystalline lens. 
To the right-hand side of the photograph is seen a large 
glass globe, which represents a jelly-like substance that 
fills the whole interior of the eye; this is called the 
vitreous humour. Inside the opened model, some lines are 
painted to represent the network of nerves connected with 
the retina , which is a complicated structure very sensitive 
to light. The inside of the model is white in order to 
show these nerves, but in reality the inside of the eye is 
black. The nerves merge together and leave the eye at the 
point indicated by the finger. They form the optic nerve , 
the fibres of which carry nervous impulses to the sensorium, 
or brain, in which the sensation of vision takes place. 

To sum up; the light enters the cornea, passes through 
the pupil of the iris, then the crystalline lens, through the 
jelly-like vitreous humour, and finally falls upon the 
retina, changes in which excite the optic nerve fibres. In 
248 





















NATURE’S CAMERA 


this way an image of the outer scene is depicted upon 
the retina, or sensitive screen. Certain nerve impulses 
reach the brain, and there the vision picture is inter¬ 
preted. 

There is a difficulty which often arises here. Like the 
image in Battista Porta's camera obscura, or in any camera, 
the image is standing on its head. Why then do we not see 
things upside down ? This has proved a stumbling-block 
to many, and yet I think there is no real difficulty in 
arriving at a common-sense view of the matter. 

I remember, many years ago, hearing a lecturer ques¬ 
tioned upon this point, and his reply seemed quite un¬ 
thinkable to me. He believed the inversion of the image 
to be rectified by a crossing of the optic nerve on its way 
to the brain. I have before me, as I write, a recent 
number of an American literary journal, in which there 
is an article dealing with this theory of vision, in which 
the crossing of the nerve fibres is said to solve the problem 
of the inversion difficulty. It is stated that this theory 
“ has gained wide acceptance among scientists.” I can 
hardly credit this statement; a common-sense view of the 
matter makes this theory quite unnecessary. 

If we think for a moment of the part which Nature’s 
camera plays in the act of vision, we find that it is in 
reality only an optical instrument. It focuses the ether 
waves of light upon its retina, and by some means or 
other the retina is thereby stimulated, causing nerve 
impulses to be transmitted to the brain. The eye is 
therefore merely a receiving instrument; it does none of 
the interpretation; that is all done at the other end of 
the optic nerve in the brain. What the brain interprets 
249 


NATURE’S CAMERA 


is the nerve impulses, not the image on the retina. It is 
therefore a matter of no moment whether the image on 
the retina is upside down or sideways up; it would make 
no difference if the image on the retina was entirely 
absent, as long as the light waves could stimulate the 
retina. By unconscious experience we have learned to in¬ 
terpret the sensations in the brain; we take no account 
whatever of the manner in which these sensations are set 
up; it is therefore quite immaterial to us whether or not 
there happens to be an inverted image produced during 
the process of vision. 

The eyes of some beetles are so constructed of a myriad 
of tiny lenses that no fewer than twenty-five thousand 
images are simultaneously thrown upon the nerve endings 
of the eye. This has been very clearly proved by taking 
a photo-micrograph through the eye of one of these 
beetles. Are we to suppose that when this beetle meets 
another solitary insect it sees an army of twenty-five 
thousand insects approaching ? Certainly npt; the beetle 
is not conscious of these manifold images. But like us, 
only in a very different form of consciousness, the beetle 
will interpret the nerve sensation and not the incidental 
myriad of images. 

If a man stands upon his head, then we see him upside 
down, as he is, because our sensation is reversed from that 
which we have when he stands upon his feet. But 
suppose the man was standing on his feet, and I could, 
by some means or other, cause an upright reflection of 
him to fall upon the sensitive screen of your eye, just as 
in a mirror, then you would see him upside down, while 
he still stood upon his feet. We cannot perform this 
250 


NATURE’S CAMERA 


experiment, but we can arrange a very simple experiment 
which completely proves that this would be the case. 

Take a piece of cardboard; a post card will serve the 
purpose. Pierce a hole at the centre of the card, using 
an ordinary pin. Hold the card up between one of your 
eyes and the light, keeping the other eye closed. Then 
look through the small pinhole, having the card a few 
inches from the eye, and at the same time bring the head 
of a pin close in front of the eye, holding the pin in an 
upright position. This will cause an upright shadow of 
the pin to fall upon the retina, and you will see the pin 
upside down. Indeed, if you were not holding the pin 
yourself you would believe that it was being held upside 
down. This experiment is well known, and is easily per¬ 
formed. It is best done with no other light in the room 
but the one which is being looked at through the card. 
The pin should be held quite close to the eye, indeed, 
touching the eyelashes. Keep the head of the pin up, 
and there is no danger of hurting the eye. A pin with a 
good large head is best. 

In passing away from this subject, I would remark 
once more that it is not the inverted image on the sensi¬ 
tive screen which the brain interprets; it is the nerve 
sensations reaching the sensorium. 

In one of the earlier chapters I passed over the fact of 
the inverted image in the camera obscura, remarking that 
no doubt it would be patent to most readers why the 
image is inverted, but that the matter would be fully 
dealt with in this chapter. It seems as though there 
could be no possible confusion here. 

If a man looks at his reflection in a looking-glass, he 
251 


NATURE’S CAMERA 


does not see himself upside down. He sees an exact 
reflection of himself, his left hand, however, becoming the 
right hand of the reflected image. It is just as though 
we had made a contact print of the man upon the glass. 
If, on the other hand, a man stands in front of a camera, 
the case is quite different; his image appears inverted 
upon the ground-glass screen. Why ? 

Imagine the lens of the camera to be at about the 
height of the man’s waist. Light is reflected from his 
face in all directions. Some rays pass over the top of 
the camera, some enter the lens. It is quite apparent 
that all the rays entering the lens from the man’s face 
are travelling in a downward direction. They pass 
through the lens and necessarily continue in a downward 
direction, so that they naturally fall at the bottom of 
the ground-glass screen inside the dark chamber. In 
similar fashion, the only rays of light reflected from the 
man’s boots which can enter the camera are travelling 
in an upward direction. These rays passing in at the 
lens continue in their upward direction till they strike 
the top of the ground-glass screen in the camera. In 
this way an image of the man’s boots appears at the top 
of the screen, while his head appears at the bottom of 
the screen. This inversion is bound to occur when an 
image is formed by rays of light passing through a small 
aperture. 

In some earlier chapters we have considered the bending 
of light by means of glass prisms. We have all seen 
the apparent bending of a stick when placed partly in 
water and held at an angle. Those of us who have tried 
to spear flounders around the sea-coast know how neces- 
252 


NATURES CAMERA 


sary it is to hold the long spear perfectly perpendicular, 
or else we are sure to give the spear a wrong thrust. 

The bending of light is very clearly demonstrated in the 
illustration opposite page 254. The left-hand illustration 
shows that the penny is 44 round the corner.” The ex¬ 
periment would still have been possible if the penny had 
been placed' quite out of sight. As the demonstration 
was to be by photography, and not by direct observation, 
I thought it better to show the exact position of 
the penny. Having taken this photograph, we let the 
camera, basin, and penny all remain in exactly the same 
positions. We carefully fill the basin with water and 
then take the second photograph. The penny is now 
quite clearly seen, but it is really 46 round the corner,” just 
as it was at first. The water has bent the rays of light 
round the edge of the basin. Rays of light passing out 
from the coin are so bent over the top of the basin that 
they reach the eye. Now the eye is not a conscious 
organ ; it takes no notice of the fact that the rays of light 
falling upon it have been bent on their journey. We 
therefore see the penny as though it were lying further 
back in the basin ; that is merely our interpretation of 
the sensation received. 

Suppose we placed a crack rifle shot in the position just 
occupied by the camera. We could safely offer him a 
handsome prize if he could strike the penny without 
breaking the basin to get at the coin. Suppose we had a 
strong iron basin, we could let the rifleman shoot all day 
at the coin, and he could never hit it; it is 44 round the 
corner.” He is really seeing the penny in a position 
which it does not occupy. 


253 


NATURE’S CAMERA 


When rays of light form an image upon the eye, we 
take no notice of how these rays may have been bent on 
their way ; we simply interpret the nerve sensation, and 
we see the object in a position it would naturally be in to 
form the said image provided there had been no bending 
of the rays. This is why the artist using the camera 
lucida sees an image of the landscape upon the paper be- 
fore him, while his friend looking directly at the same 
paper sees nothing but a blank paper. The artist alone 
sees the picture, because the rays of light reflected by the 
landscape are bent by the glass prism and cause an image 
to be formed upon his eyes. 

It will be of interest to see how the “ sensitive plate ” is 
operated in Nature’s camera. Is it a photographic action ? 

It was supposed for a very long time that we had three 
sets of nerves in the retina, one of which was sensitive to 
red, another to green, and the third to violet rays of 
light. This theory seemed to make matters fairly clear, 
but the three sets of nerves, or nerve endings, could not 
be found in the retina. 

Within recent years it has been discovered that in the 
frog’s eye the retina secretes a substance, which is of a 
purple colour, and has been named purpurine. The purple 
matter is bleached to a dull grey by light. Here we have 
the chemically prepared photographic plate ! This photo¬ 
graphic substance is held in the meshes of the retina, 
which spreads over the interior of the eye. Any chemical 
change in this purpurine is appreciated by the nerves and 
immediately telegraphed to the brain. In the human 
eye, and more especially in the part most sensitive to 
light, the so-called yellow spot, there is no purple stuff, 
254 



The only difference between these two photographs is that the basin in the left-hand picture has no water in it, whereas that in 
the right-hand picture has. The coin and basin are lying in exactly the same position in both photographs, and the camera was 
in no way disturbed. (See chap, xvii.) 
































NATURES CAMERA 

but there are probably other colourless chemical sub¬ 
stances. 

This theory appears to solve many problems. What 
about colour ? Many persons cannot see the colour red; 
we therefore suppose that some chemical ingredient is 
wanting. It is quite possible that many people go through 
life without the knowledge that they cannot see red as 
other people do. Even such an observant man as the 
great John Dalton, the founder of modern chemistry, was 
twenty-six years of age before he discovered that he was 
“colour-blind.” The occasion of his finding out this 
defect in his vision is very amusing. Thinking to take 
his mother home a useful birthday present, and seeing in 
a shop window a pair of stockings marked “silk and 
newest fashion, 11 Dalton promptly secured these as a suit¬ 
able gift. He was very surprised when his mother said, 
“ Thou hast brought me a pair of grand hose, John, but 
what made thee fancy such a bright colour ? Why I can 
never show myself at meeting in them. 11 Poor Dalton 
said that the stockings being of a “ dark-bluish-drab 11 he 
considered them to be a very proper sort of go-to-meeting 
colour. His brother Jonathan was called in to settle the 
disputed point, but he at once agreed with John, and the 
two brothers came to the conclusion that the old lady's 
sight was strangely out of order. Deborah, thinking that 
it was her sons 1 sight that was at fault, consulted some 
of the neighbouring wives. She soon returned with the 
verdict “ Varra fine stuff, but uncommon scarlety, 11 
Shortly after this Dalton directed the attention of the 
scientific world to this “extraordinary fact relating to 
the vision of colours. 11 


255 


NATURE’S CAMERA 


There is another phenomenon which seems to bear out 
this theory of the photographic chemicals in Nature’s 
camera. It is a well-known fact that if one stares steadily 
at a red colour for a minute, one will then see a sheet of 
white paper appear green. Just as I write these lines I 
have beside me three sheets of coloured glass—a red, a 
green, and a violet. I have been looking steadily at a 
bright incandescent gaslight through the red glass, and 
now when I look directly at the white paper upon which 
I am writing I see it a decidedly greenish-blue colour. I 
now look at the light, for a minute, through the green 
glass. When I look back to my paper it is a strong 
crimson-pink; the effect in this case is to me more striking 
than the first. Now I look through the violet glass, and 
then at my paper, which now appears a decided yellow. 
Of course, these effects might be explained by the theory 
of three different sets of nerves, one set of nerves becom¬ 
ing fatigued by looking at the red, and so on. We have 
no evidence of there being three sets of nerves, and the 
chemical theory seems to me much more reasonable. 
We imagine this chemical substance being acted upon by 
red rays, causing all the red ingredient to be decomposed. 
We immediately throw a white light upon this altered 
substance, and while the white light is composed of red, 
green, and violet rays, its red rays can find no chemical 
substance to act upon. Red is therefore absent from the 
sensation produced, and we see a combination of the other 
two rays, a greenish blue, and so on with the others. 

Now it seems quite reasonable to suppose that in a case 
of colour-blindness the eye itself is quite normal, but 
there is a defect in the chemical laboratory which pro- 
256 


NATURE’S CAMERA 


duces the sensitive stuff, and the particular ingredient 
which is affected by red rays is not manufactured at all. 
We therefore believe that the part played by the retina 
in regard to vision is a purely photographic process. 

Nature has provided us with two separate cameras, not 
simply that we may have a spare one in case of accident, 
nor yet only that we may have a wider range of vision. 
Each eye produces a different picture; it looks at an 
object from a slightly different position from its neigh¬ 
bour. It is the combination of the two pictures which 
gives us the impression of the solidity of things. 

Hold a pencil up in front of you, close one eye, and let 
the pencil cover some distant object from view. Keeping 
the pencil in the same position, look at it with the other 
eye; the pencil appears in quite a different position. 
You thus observe that the two pictures produced in your 
eyes are different from each other. Your left eye really 
sees more of the one side of an object than the other, 
while the right eye sees the other side best. This is 
quite apparent in the illustration opposite page 258. 
These two photographs have been taken by a double 
camera, or practically two cameras. The two lenses are 
mounted a little distance apart, just as our eyes are. It 
is quite apparent that the camera which took the left-hand 
picture has had a different view from the camera which 
took the right-hand picture. In the latter the little 
girl’s head appears quite close to the left-hand bank, 
whereas in the other picture her head appears close to the 
opposite bank. 

Here we have imitated Nature’s twin cameras ; we have 
produced two different images just as our eyes do; but 
257 


R 


NATURES CAMERA 


how are we to combine these two effects P When you 
look at the illustration, each eye sees both pictures. We 
must throw each picture separately, the one on the right 
eye and the other on the left eye. Some people are able 
to adjust their eyes in such a manner that the two 
pictures each fall separately upon the proper eye, but to 
most of us this is not easily accomplished. We are 
all familiar, no dpubt, with the simple instrument known 
as a stereoscope . It consists of two lenses with a dividing 
partition, and is so arranged that when one looks at a 
stereoscopic pair of photographs, such as that shown in 
the illustration, each eye sees only its own picture. The 
pictures are in a sense recombined in the brain. We then 
have two different views upon the sensitive screens of our 
eyes, and we see the objects stand out in bold relief, just 
as we do in viewing the original objects. 

When one uses a stereoscope for the first time, one is 
very much surprised at the splendid perspective and the 
enhanced reality of the scene. 

I remember on one occasion, before stereoscopes were so 
well known as they now are, I found an enthusiastic 
amateur busily mounting duplicates of some of his photo¬ 
graphs on stereoscopic cards. He was very disappointed 
when I pointed out that his work was useless, and that he 
must take two different photographs, each photograph 
being really a different view of the scene. 

Quite good stereoscopic photographs may be taken by 
a single camera, provided one arranges a base upon which 
the camera may be moved into two positions. First of all 
one photograph is taken, and then the camera is moved 
along so that the lens is two and a half inches farther to 
258 


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NATURE’S CAMERA 


one side, and a second photograph is taken from that 
position. It is much more convenient, however, to have 
the camera divided into two and the two lenses placed 
two and a half inches apart. The two pictures are then 
taken simultaneously, thus permitting of instantaneous 
photography. 

Some readers may have seen a stereoscopic photograph 
of the moon, and yet it must be apparent that any two 
photographs, taken by a stereoscopic camera, of so distant 
a body, must be practically the same picture. The way 
in which the stereoscopic photographs of the moon have 
been taken has been to take two separate photographs at 
different periods, for when the moon has made a circuit 
round the earth she does not arrive back at the very same 
/ position from which she set out. Suppose we had a complete 
circle drawn in the heavens, around the earth, and fixed 
in a permanent position. The moon sets off from one 
point upon this circle, but when she returns we find that 
she is either above or below this line; we therefore get a 
slightly different view of her. Therein lies the photo¬ 
grapher’s opportunity of securing two photographs for 
his stereoscope. 


259 


CHAPTER XVIII 


SOME INTERESTING 
ACHIEVEMENTS 

The largest photograph in the world—How it was developed—En¬ 
larging photographs—An amusing incident—A gigantic camera— 
The photographer inside the camera—Tele-photography—Good 
pictures taken from a distance of one mile—Nature photography 
—Ballooning and photography—Photographing the New York 
subway—Calculating exactly when a photograph was taken— 
Faked photographs. 

T 7HILE America is the country of big things, 
\/\/ Germany can boast of having produced the 
largest photograph in the world. 

The accompanying illustrations (see frontispiece) show 
how this gigantic photograph was handled. In the larger 
illustration we see the great photograph mounted on a large 
wheel, or drum, having a circumference of forty-one feet. 
A number of very large tanks had to be constructed so 
that the gigantic print might be developed, cleared, fixed, 
and washed. These tanks were so heavy that it was 
necessary to have them on wheels, and to construct a 
miniature railway track, along which they might be moved 
as desired. The washing tank required to be fifty feet in 
length, six and a half feet wide, and two and a half feet 
deep. Where is the dark room to hold such enormous 
developing baths, etc.? The only way out of the difficulty 
260 


INTERESTING ACHIEVEMENTS 


was to develop the photograph in the open air during the 
night. 

Some idea of the magnitude of the task may be 
gathered from the fact that more than ten thousand cubic 
feet of water was used in washing the print. 

The subject of the photograph was the Bay of Naples. 
The complete panoramic picture measured about forty 
feet by five feet. It is evident that no camera could hold 
a plate or film of such a size. The method of obtaining 
the photograph was as follows :— 

First of all six panoramic views were taken; each of 
these measured ten and a half inches by eight inches. 
These six photographs contained the whole detail of the 
final picture; joined together they would form a minia¬ 
ture of the gigantic photograph. From each of these 
six photographs an enlargement was made. The process 
of enlarging is well known, but will be explained a little 
later. Each enlargement measured about six and a half 
feet long by five feet, and to obtain these it was necessary 
to have a very large lens, measuring one foot in diameter. 
While these enlargements were made separately, they were 
not made on separate sheets of paper. One long sensitised 
paper, the complete foundation of the final picture, was 
prepared. Then an enlargement of the first negative was 
made directly upon this paper, next to that a similar en¬ 
largement of the second negative, and so on, until the 
whole six enlargements had been made in succession. This 
must have been a difficult task, for the picture is not seen 
upon the paper until the complete bromide print is 
developed later. How very ingeniously this difficulty was 
overcome was shown by the final result. It was practically 
261 


INTERESTING ACHIEVEMENTS 


impossible to detect the boundary line of any two 
plates. 

Then came the task of developing the hidden or 
latent image of the complete photograph. From the 
illustration it will be seen that twelve men were re¬ 
quired to look after the developing of this one great 
photograph. The man on the top of the ladder is pro¬ 
jecting iced acetic acid, from a hand-pump, on to a part 
of the photograph which is already sufficiently de¬ 
veloped ; the action of this acid being to stop development. 
At other parts of the photograph, where the image was 
faint, it was found necessary to force the developing by 
applying an energetic developer by means of sponges. 

In the smaller illustration below, the print is being un¬ 
reeled from the developing wheel into the clearing bath, 
and this illustration will probably give the reader a 
better impression of the length of the photograph. A 
large number of basketed jars containing the different 
chemicals will be seen at the side of the developing 
wheel, large quantities being required to fill the different 
tanks. Altogether the production of so large a photo¬ 
graph is remarkable. 

It is possible that some readers may not be familiar 
with the process of enlarging. The method is very 
simple. It will be evident that if one were to use a 
negative as a magic-lantern slide, one could project an 
image on to a white sheet. Instead of throwing the image 
on to an ordinary lantern sheet, let us replace the insensi¬ 
tive sheet by a large piece of sensitised photographic 
paper. All the variety of light and shade will be faith- 
262 


INTERESTING ACHIEVEMENTS 


fully recorded by the photographic paper. We might 
use ordinary printing-out paper if the source of light we 
were using was good strong daylight, and provided we 
could depend on a sufficiently constant light. In Great 
Britain, however, it is usual to employ a bromide emul¬ 
sion paper, which is very much more sensitive to light, 
and with which an artificial source of light may be used. 
It has already been noted that the image upon the 
bromide paper is invisible until it is chemically de¬ 
veloped. 

If the photographer, using bromide paper, desires to 
use daylight, he darkens his room by means of a shutter 
or cloth screen, leaving only a small window into which 
the back of his camera will tightly fit. He now uses his 
camera as a daylight magic lantern. He places the nega¬ 
tive of which he desires an enlargement in the back of 
his camera, just where the ordinary photographic plate 
goes. The daylight enters the camera through this 
negative, and an image is projected into the dark room. 
He focusses this image upon a piece of paper, and when it 
is sharp he replaces the paper screen by a sheet of bromide 
paper. After a suitable exposure the bromide paper is 
developed and a record of the enlarged image is secured. 

When it is desired to enlarge pictures by means of arti¬ 
ficial light, then a special projecting apparatus is used, 
this being simply a specially constructed magic lantern. 

It is an interesting fact that a negative film may be 
enlarged directly by chemical means. The negative is 
first of all placed in a bath of ammonia, and in about two 
hours the film is freed from its glass support. The film 
then distends, the process being hastened if necessary by 
263 


INTERESTING ACHIEVEMENTS 


the addition of a little hot water. The enlarged film is 
then floated on to a large glass plate and allowed to dry. 
It is obvious that the whole limit of enlarging by this 
process cannot be very great, probably not more than 
twice the size of an ordinary negative. Then again, in the 
event of any accident, the original negative is lost. 

This distension of the negative film reminds me of an 
amusing incident which happened quite accidentally. A 
photograph had been taken of some friends, and in the 
amateur’s haste to get the negative dry enough to print 
from he placed it near a fire. The negative film distended, 
but only in one direction, and the resulting prints were 
very comical, every person was so short and stout. The 
effect was exactly that seen in a curved mirror, such as is 
sometimes used at exhibitions for affording amusement. 

I believe Glasgow can boast of having possessed the 
largest camera in the world. Many years ago the late 
John Kibble, who erected the handsome greenhouses, 
known as the “ Kibble Palace,” in the Botanic Gardens of 
Glasgow, was the possessor of an immense camera. It 
was mounted on wheels and drawn by a horse ; the whole 
arrangement being in appearance rather like a furniture 
removal van. This camera was used in the days of wet 
collodion plates, so that it was necessary to prepare the 
plates immediately before taking the photographs, and 
then develop the plate immediately afterwards. Where 
are the plates to be prepared and developed ? Inside the 
camera itself. It is curious to think of the photographer 
and his assistant being both closeted inside the camera 
while a photograph was being taken. 

264 


INTERESTING ACHIEVEMENTS 


First of all the glass plate had to be coated with the 
sensitised chemicals, in the method described earlier under 
Scott Archer’s name. Then the picture had to be 
focussed on a white screen, in order to find the exact posi¬ 
tion in which to place the photographic plate. While the 
plate was being exposed the photographer and his assistant 
had to keep clear of the projected image. Then when it 
was deemed that the plate had been sufficiently exposed, 
the plate was straightway developed. 

Some excellent photographs were taken, by this gigantic 
camera, in the busy streets of Glasgow. It is indeed 
remarkable that it was possible to take instantaneous 
photographs with so large a camera. 

An elderly gentleman, who was a contemporary of 
Kibble, tells me that he was inside this huge camera on 
several occasions, and the arrangements for preparing and 
developing the plates were most ingenious. 

Facing page 284 we have an illustration of tele-photo¬ 
graphy. The upper illustration is a photograph of 
St. Alban’s Abbey taken from a distance of one mile. 
The picture of the abbey itself is necessarily very small, 
and one cannot see much detail. 

The lower illustration is a photograph taken from exactly 
the same position, one mile distant, but this has been 
taken through a tele-photo lens. In this picture one sees 
the abbey very distinctly. It is difficult to realise that 
the trees, so clearly seen in the foreground, were nearly 
one mile away from the camera. The little square marked 
off in the upper illustration shows exactly how much of 
that photograph is contained in the lower illustration. 

265 


INTERESTING ACHIEVEMENTS 


Tele-photography is practically photography through 
a telescope, the tele-photo lens acting as the telescope. 
There are decided advantages in the tele-photo lens. 
It admits far more light than a telescope would do, 
and it is so constructed that its focus does not require 
a long extension of the camera. 

There are many useful applications of tele-photo lenses. 
We shall see one great use of these in the chapter on 
photographing the stars. Tele-photo lenses have also been 
of much service in photographing the architecture of 
inaccessible parts of a building and mountain scenery. 
Another interesting application is in photographing birds 
in the air or in their nests. One great advantage in 
natural history work is that the photographer can obtain 
a near view without going close up to the animal and 
possibly disturbing it. 

In connection with nature photography, the two brothers 
Kearton (England) have done a great deal of most in¬ 
teresting work. Their photographs of birds and nests 
are well known through their lectures and writings. 

In looking at the illustrations which they have published 
from time to time, one sees the great advantage of getting 
actual photographs of birds upon their nests, etc. It would 
be an interesting occupation to compare many artists’ draw¬ 
ings of birds with the actual photographs now obtained. 
Our present interest, however, lies in the taking of the 
photographs. 

It is quite evident that the Keartons are enthusiasts. 
They relate that in their photographic expeditions they 
“ have slept for nights together in empty houses and old 
266 


INTERESTING ACHIEVEMENTS 


ruins, descended beetling cliffs, swum to isolated rocks, 
waded rivers and bogs, climbed lofty trees, lain in wet 
heather for hours at a stretch, tramped many weary miles 
in the dark, spent nights in the open air on lonely islands 
and solitary moors, endured the pangs of hunger and 
thirst and the torturing stings of insects, waited for days 
and days together for a single picture, and been nearly 
drowned, both figuratively and literally.” 

This enthusiasm was born in these photographers, for 
one of them tells how when he was only nine years of age 
he went out nest-hunting, and coming upon a nest which 
was new to him, he determined to wait till the bird re¬ 
turned. Hiding himself in the hedge, the little fellow 
waited patiently, but the bird was long in coming; dark¬ 
ness fell, and sleep soon overtook the young enthusiast. 
It was only when his people became alarmed at his con¬ 
tinued absence, and a search party had been sent out, that 
the boy was aroused from sleep. 

While the Keartons are most desirous that amateur 
photographers should betake themselves to the fields, they 
very wisely point out that such photographs as they them¬ 
selves have obtained are not to be got without a great 
deal of patience. In order to let the would-be photo¬ 
grapher know what he must be willing to endure, one of 
them says: “ Kneel in one position for half an hour and 
look steadfastly through the keyhole of a door, multiply 
the time and pain by eleven, and add a complete dis¬ 
appointment, when some idea will be gained of what has 
happened to my brother and myself over and over again 
during the last few years.” 

The Keartons devised many means of getting their 
267 


INTERESTING ACHIEVEMENTS 


camera close up to the nests. One plan was to have the 
camera enclosed inside a stuffed sheep, with the lens 
peeping out through a hole in the breast. The operator 
then hid in a rush-covered tent, whence he could watch 
for the bird’s return, and “pull the trigger” from his 
hiding-place. At other times the photographer con¬ 
cealed himself and his camera inside an imitation ox, 
taking the photographs through a hole in the breast of 
the stuffed animal. 

Another prominent nature photographer, in quite a 
different field, is Herr C. G. Schillings, of Germany. It 
was, indeed, a bold idea to photograph wild animals in 
perfect freedom. Imagine any man going right among the 
big wild game of equatorical East Africa and calmly 
taking their photographs. 

Professor Lambert, of Stuttgart, has referred to 
Schillings’ photographs in the following terms: “ These 
pictures are of the greatest importance. In them the 
wild animals of Africa will live on long after they have 
been sacrificed to the needs of advancing civilisation.” 

Some of Schillings’ most remarkable photographs were 
obtained during the night by means of a flash-light, and 
owing to this fact he has entitled his work With Flash¬ 
light and Rifle. On one occasion he photographed three 
full-grown lionesses as they came down to a pool to drink 
during the night. Imagine a man lying in wait in the 
dark midnight, hoping some savage beast would come close 
enough to him to be photographed! 

In another photograph a lioness is seen actually spring¬ 
ing upon an ox, while a large lion, having allowed the 
268 



Photo by Signor T. M. Bianchi, Madeira 

Portuguese Diving 

The whole detail of this living scene was recorded by the great artist, Light, in one five- 
hundredth part of a second. This exposure was obtained by means of a Thornton-Pickard 
Focal-plane shutter. 















INTERESTING ACHIEVEMENTS 


lioness, as is his custom, to make the attack, comes to help 
to devour the prey. In one photograph a lioness was 
taken at a distance of only three yards. 

On many occasions while Herr Schillings was following 
some other animal, such as a gazelle, he suddenly found 
lions and lionesses, within a hundred paces, stealthily ap¬ 
proaching him. One can scarcely imagine the nerve- 
power required to keep cool under such circumstances. 

Among Herr Schillings’ “ sitters ” there were huge 
elephants, rhinoceroses, hippopotamuses, giraffes, zebras, 
hyaenas, etc. These photographs, of animals in perfect 
freedom at their own home, were not obtained without 
much experience gained through many disappointments 
in previous expeditions made by Herr Schillings. This 
gentleman has the rare combination of being an expert 
photographer and a fearless hunter. 

Some interesting photographs have been taken from 
balloons, and it is a strange fact that some of the best 
photographs have been obtained on dismal rainy days. 
The reason why moisture in the air aids aerial photo¬ 
graphy is doubtless because it prevents the dust motes from 
reflecting the sunlight. It is quite impossible to take 
a photograph from a balloon at a height of four thousand 
feet because of this reflection from the dust motes. 

One well-known aeronaut, the late Rev. James Bacon, 
received a very strange request from the Russian Govern¬ 
ment. It was shortly after the tragic incident in the 
North Sea, on which occasion a British fishing fleet was 
fired upon by some Russian battleships which were proceed¬ 
ing to the seat of the Russo-Japanese War. The Russians 
269 


INTERESTING ACHIEVEMENTS 


declared that some Japanese torpedo-boats had been seen 
among the fishing boats, and they were naturally anxious 
to prove that this was the case, if they possibly could. 
The Russian Embassy requested the British aeronaut to 
proceed to the scene of the mishap in his balloon, and 
while hovering over the waters to take photographs 
which would show the depths beneath. The idea was 
to photograph the phantom torpedo-boat which the 
Russians declared they had sunk. Although it is quite 
possible to take good snapshots from a balloon of the 
regions below the sea-level to a considerable depth, 
it is needless to say the aeronaut did not accept the com¬ 
mission. 

When one of the biograph companies undertook to 
take animated pictures in the New York subway, they 
took on hand a very difficult task. It is apparent that 
the light must be very good if one is to take about 
one thousand photographs in each minute. It would 
have seemed to the ordinary photographer to be a 
practical impossibility to produce sufficient light in the 
underground tunnel to enable such photographs to be 
taken. The American photographers thought differently. 
They fitted a large railway truck with hundreds of very 
powerful electric lamps. They used what are known as 
mercury vapour lamps; these give forth a rather hideous 
light, the red rays being absent. This, however, is a 
splendid photographic light. 

The total light produced was equivalent to fifty-four 
thousand candle-power. It would require between three 
and four thousand ordinary glow lamps to produce this 
270 


INTERESTING ACHIEVEMENTS 


candle-power, and even then the total light would be 
very weak photographically when compared with the 
truck-load of mercury vapour lamps. 

The photographs were taken from a moving train, 
which practically chased one of the regular trains 
through the tunnel. The powerful light was carried 
by the second train, and the light was thrown imme¬ 
diately ahead so as to light up the rear of the regular 
train. The resulting pictures showed the train flying 
through the tunnel, and then drawing up at one of the 
stations. Here some passengers were seen alighting, while 
others entrained. Then off went the train once more. 
The pictures attracted considerable attention because of 
the gigantic lighting scheme which was necessary. 

If some one were to hand you the photograph of a 
building, and ask you to calculate the exact position from 
which the picture had been taken, you might not be will¬ 
ing to undertake the task, but the request would appeal 
to you as being quite a reasonable problem. 

If, however, some one were to hand you a similar 
photograph and ask you to calculate the day and the 
hour when the photograph was taken, you would doubt¬ 
less consider the request as a jest. This seemingly im¬ 
possible task was undertaken, some years ago, by a 
mathematician. 

The subject was a photograph of one of the American 
observatories in Nebraska. This photograph was found 
in one of the old catalogues of the observatory, but it 
was not known when, nor by whom, the photograph had 
been taken. Professor Rigge set himself the task of 
271 


INTERESTING ACHIEVEMENTS 


calculating the exact date and hour at which the photo¬ 
graph had been taken. 

Fortunately the sunlight had been strong, so that the 
shadows cast by different parts of the buildings were very 
marked. By means of these shadows the mathematician 
was able to calculate the exact position of the sun in the 
heavens. This was no light task. But as the sun has a 
twofold motion, and as each motion is independent of 
each other, a shadow gives us both the time of the day 
and the day of the year. 

Having obtained the exact position of the sun, the 
professor found that there were two different dates during 
the year on which the sun was in this particular position. 
One day was the 2nd of May, and the hour a few 
minutes past three o’clock in the afternoon. The other 
possible date was in the month of August. A close 
examination of the grass and the trees in the photograph 
decided that the earlier date was the correct one. 

Having calculated the exact hour and the day of the 
year upon which the photograph was taken, how could 
the particular year be determined P The shadows would 
be the same each year at the same time, so some other 
evidence must be appealed to. As the photograph ap¬ 
peared in the observatory catalogue for the year 1894, it 
was clear that the picture had been taken before that 
date, but it might have been taken many years earlier. 
How then could the particular year be discovered ? 

It so happened that the weather vane of the observa¬ 
tory was distinctly seen in the photograph, and its 
direction was due north-west. A continuous record of 
the direction of the wind is kept in the observatory, so it 
272 


INTERESTING ACHIEVEMENTS 


was an easy matter to find out in which year the wind was 
due north-west at three o’clock on the 2nd of May. It 
was found that the wind had been due north-west on that 
day and hour in 1893. 

Further evidence could be brought forward by the 
photograph. Some trees at a distance of three miles were 
very distinctly seen, and this fact indicated a particularly 
clear atmosphere. Therefore the barometer must have 
been high, and the wind must have been steady for several 
hours. All these conditions exactly agreed with the 
records for the 2nd of May, 1893, while an examination 
of the records for the same day in 1894, 1892, 1891, 
1890, etc., showed that in none of these years did the 
necessary conditions prevail. 

It was therefore definitely proved that the photograph 
had been taken at 3 p.m. on the 2nd of May, 1893, the 
achievement being quite worthy of 46 Sherlock Holmes.” 
In order to show that the day and hour were correct, a 
duplicate photograph was taken in the following summer, 
at 3 p.m. on May 2nd, when every shadow was found 
to coincide exactly with those in the original photo¬ 
graph. 

While a simple photograph is a truthful witness, it is 
apparent that it is a witness which may be easily tam¬ 
pered with. If a photograph could be used as a witness 
in a law court, then a criminal might be able to prove an 
alibi by trickery. It is quite an easy matter to insert 
one’s photograph into a second photograph, and then re¬ 
produce it as a complete picture. A criminal might have 
his photograph inserted into some picture which it could 
273 


s 


INTERESTING ACHIEVEMENTS 


be proved was taken in a distant town on the day and at 
the hour of the alleged crime. The criminal could not 
have been at the place of the crime, as the photograph 
would “prove” him to have been in a distant town. 

When an heir to the Crown Prince of Germany was 
born, there immediately appeared a picture post card 
with a photograph of the Kaiser with his little grandson 
in his arms, while the Crown Prince and Princess stood 
close beside him. The photograph appeared within 
twenty-four hours of the birth of the future ruler, and 
before the Kaiser, who was in Norway, had ever seen his 
little grandson. This “ faked ” photograph was the 
subject of an action at law, brought by a photographer 
who did photograph the royal group later. 

Quite a lot of legitimate amusement may be got by 
“ faking ” photographs. A man may be shown sitting at 
a table earnestly playing cards with himself as his 
opponent. Or, again, quite a natural photograph may 
be produced of the man having a heated discussion with 
himself. Faked photographs occasionally appear in our 
law courts, and it has been repeatedly proved that 
to issue a faked photograph as genuine is distinctly 
illegal. 


274 


CHAPTER XIX 


PHOTOGRAPHING THE STARS 

Early daguerreotypes of the moon—The astronomer’s camera—A 
difficulty overcome—Some useful applications of photography— 
Photographing stars never seen by man—Photographing an extinct 
star—Discovery of small planets—Photographic discovery of 
Saturn’s ninth satellite—Going round the wrong way—Wonderful 
maps of the moon—Vast nebulae that dwarf the solar system— 
Photography and solar eclipses—Photography and the spectro¬ 
scope—How we tell what the stars are made of—Some stars 
approaching us—Discovery of a double star—An amusing incident 
on the Alps—Photography’s important part in astronomy. 

P HOTOGRAPHY was in its very infancy when it 
was suggested to try and obtain pictures of the 
heavenly bodies. The first photographic studios 
were just being opened (1840) when Dr. Draper, of New 
York, succeeded in taking the moon’s photograph by the 
daguerreotype process. These early attempts were very 
imperfect, but some fair specimens of lunar photographs 
were shown at the great London Exhibition of 1851. 
These were also taken by an American. 

The first idea was simply to use a telescope as the lens 
of a camera, and this method continued up till 1870. 
Why not use an ordinary camera ? We may easily obtain 
a photograph of the full moon in an ordinary camera, 
but the image will be very small, probably about one- 
tenth part of an inch. To obtain a larger image we must 
use a lens having a greater magnifying power. 

Suppose, then, that we have a camera fitted with a 
275 


PHOTOGRAPHING THE STARS 


special tele-photo lens, and we try to take a photograph of 
the full moon. We find that our efforts have met with 
success, and so we decide to try and photograph some of 
the distant stars. This time we meet with complete 
failure, and we find the reason of our failure to be that 
the stars will not stay in one place long enough to let us 
get a photograph. Asa matter of fact, it is our camera 
that will not remain in one position; it and we with it 
are all moving through space. With our faithful moon 
we are waltzing around the sun. It is the turning motion 
which bothers us when we try to take a photograph of 
the heavens. We did not notice this when we took a 
photograph of the full moon, because the light was so 
bright that we practically took a snapshot of it. The 
exposure was only a fraction of a second. We find, how¬ 
ever, that so very little light reaches us from some stars, 
that these ether waves of light require several hours of 
constant action upon the chemicals on the photographic 
plate before they can make any impression. Herein lies 
our difficulty, for during these hours the camera has been 
turned round in the waltz to quite a different position. 
Indeed, it has never remained long enough in one position 
to receive any impression of the star which we were 
endeavouring to photograph. 

How, then, are we to overcome this difficulty? We 
must keep turning our camera round in the opposite 
direction to that in which the earth is carrying it, so that 
the eye of the camera will remain steadily fixed upon the 
star. Of course, it appears to us as if the stars were 
moving and we ourselves were stationary, for we have no 
sensation of movement through space; everything, in- 
276 


PHOTOGRAPHING THE STARS 


eluding our atmosphere, is going with us, and no resist¬ 
ance is offered to our progress. 

The large telescopes had already been fitted with clock¬ 
work, which kept them moving round at the required 
speed to counterbalance our movement in the great 
celestial waltz. The camera could therefore be clamped 
on to the side of the telescope, so that it too would keep 
a star in view. A star appears as a mere point of light, 
so that any movement will be very noticeable. Even the 
best clockwork may not serve to keep the camera quite 
steadily on the star for a very long exposure. In this 
case the observer must watch the star through a small 
telescope which is moving along with the camera. This 
telescope is provided with cross-wires in the eyepiece, so 
that the observer may get the star into a definite posi¬ 
tion as regards these cross-lines; and if the clockwork 
tends to take the camera too fast or too slow, he may 
retard or hasten the clockwork to rectify the amount of such 
error. In this way excellent photographs have been taken. 

It will be of most interest to the reader to know what 
useful purposes photography has served in the study of 
the celestial bodies. We are accustomed to hear stars 
described as of the first magnitude , or the sixth magnitude , 
and so on. This is really no description of their relative 
sizes; it refers to their apparent size. One star might 
appear larger than another because it happened to be 
nearer to us. Even the sun and the moon appear to us 
to be very much the same size, and yet we know that the 
diameter of the sun is four hundred times greater than 
that of the moon. Again, one star might appear larger 
than another because it had a greater luminosity. 

2 77 


PHOTOGRAPHING THE STARS 


We see that the magnitude really tells us nothing but 
the apparent size of one star compared with another, but 
astronomers have found it convenient to describe the stars 
in this comparative manner. Stars of the first to the 
sixth magnitudes are visible to the unaided vision. Those 
of the seventh magnitude and upwards can only be 
seen with the aid of telescopes, and may therefore be 
called telescopic stars. As more powerful telescopes were 
made further ranges of stars were brought to view, till 
the number of magnitudes was increased to twenty. It is 
obvious that a question of the personal equation comes in 
here, for one observer might describe a certain star as be¬ 
longing to the tenth magnitude, while another observer 
might say that it should belong to the eleventh magni¬ 
tude, and so on. Photography can supply a more reliable 
comparison. 

If we expose a photographic plate to a group of stars 
for five seconds, only the brightest stars will be able to 
impress their images upon the sensitive plate. A second 
and similar plate exposed for ten seconds will reveal some 
of lesser brilliancy, as well as those already seen upon the 
first plate. A third plate exposed for twenty seconds will 
reveal more, and so on. If we go on increasing the time 
of exposure in this manner until we are into hours instead 
of seconds, we shall find that after we have photographed 
all the stars visible in the best telescopes, we may still con¬ 
tinue adding to the numbers on the photographic plate. 
We are then photographing stars which have never been 
seen by mortal man. 

Astronomers have reason to believe that some of these 
stars which we have just been considering are so very far 
278 


PHOTOGRAPHING THE STARS 


distant from us that the ether waves of light sent out by 
them take many thousands of years to reach us. This 
seems almost incredible when one considers the fact that 
light travels at the enormous speed of nearly two hundred 
thousand miles per second. Here is a curious thought. 
We might set up a camera to-day and take a photograph 
of stars which ceased to send forth light before the Flood. 
Indeed, it may be that we have photographed stars which 
disappeared before man ever lived upon this earth. It 
would not affect this statement even if we granted that 
man may have been a tenant of this planet for one 
hundred thousand years. 

The largest possible number of stars to be seen by the 
unaided vision certainly does not exceed five thousand. In 
one part of the heavens as many as two hundred thousand 
stars have been carefully mapped out, with the aid of 
powerful telescopes. In the same area as many as two 
million stars have been detected by photography. 

Picture the astronomer of not so long ago sitting 
night after night at his telescope hard at work making a 
map of a certain part of the heavens. What a tedious 
and difficult task to fill in all these little specks in their 
proper places. Then picture the present-day astronomer 
setting his camera in any desired position and in a few 
hours obtaining an absolutely true chart. Photography 
accomplishes in a few hours a task which would otherwise 
require years of patient labour. 

The astronomer is keen to note any change among the 
heavenly bodies, and so he repeatedly compares the 
heavens with previous charts. When an additional star- 
like object does appear, he watches it carefully for hours 
279 


PHOTOGRAPHING THE STARS 


to see whether it is a fixed star or a small planet, known as 
an asteroid. If he finds that it has any forward motion, 
then he knows that it is an asteroid. Nowadays, photo¬ 
graphy is a useful assistant in determining this point. On 
the negative all fixed stars will appear as little dots, while 
the small planet will appear as a streak, for it will have 
made a slow procession across a part of the plate. It will 
be remembered that the motion we have given to the 
camera, by clockwork, merely keeps the camera pointing 
steadily at the stars, so that any movement of the small 
planet among the stars will be detected. 

The physical nature of these asteroids is not known, 
but it is supposed by some astronomers that they may be 
fragments of some great planet disintegrated in past 
ages. The largest of these small planets is about five 
hundred miles in diameter, or, roughly, fifteen hundred 
miles in circumference. It would be little more than a 
whole day-and-night journey to go round one of these 
asteroids in a non-stop express train. Other asteroids are 
very much smaller, and may not exceed fifty miles in 
diameter. Since photography has been called in to assist, 
there have been some thirty new asteroids discovered 
every year. As many as three of these small planets 
have been discovered on one photographic plate. The 
present total is between five and six hundred, and it is 
believed that we have now photographed all the asteroids 
whose diameters exceed fifty miles. Like all other planets, 
these asteroids are lighted by the sun and are compara¬ 
tively near to us, while the stars, which are themselves 
suns, are millions of times farther off. 

While we think of those asteroids as very small bodies 
280 


PHOTOGRAPHING THE STARS 


compared with the great planets, we must not picture 
them as being of merely meteoric size. Many of them 
are about the size of Great Britain, and they move around 
the sun in the space between the four inner planets and 
the four outer or giant planets. 

A century ago we believed that only three of the 
planets had satellites—faithful attendants like our moon. 
Now we know of five such systems, and it was photo¬ 
graphy that discovered two of the new satellites for us. 

There is an interesting point in connection with the 
discovery of one of these two satellites. In 1898 it was 
announced that a new satellite (Phoebe) had been dis¬ 
covered moving around Saturn. This made the ninth 
satellite for the mysteriously ringed planet, but the an¬ 
nounced discovery was not generally accepted as fact. 
The only evidence was a photographic plate ; there must 
have been some mistake. All attempts to find this 
satellite with the best telescopes failed; the beautiful and 
youthful Phoebe must be a myth, like the great Apollo 
himself, from one of whose epithets the word Phoebe had 
been coined. 

Long before this time one observer believed that he 
had discovered another planet, to which he gave the name 
Vulcan , but this supposed discovery was never confirmed, 
although many photographic plates were exposed to that 
part of the heavens in which Vulcan should have been. 
The supposed discovery was therefore determined to be 
an error. When the announcement of Phoebe’s discovery 
was made and astronomers could not find the satellite 
with their telescopes, one astronomer jocularly suggested 
that Phoebe had gone off to look for Vulcan. Years went 
281 


PHOTOGRAPHING THE STARS 


past and nothing more was heard of Phoebe, till an 
astronomer in another quarter also found this satellite of 
Saturn upon a photographic plate. 

If some amateur astronomer had suggested that the 
reason why Phoebe could not be caught by the astrono¬ 
mer’s telescope was that the satellite was moving around 
Saturn in the opposite direction to all other satellites, it 
would, no doubt, have caused amusement in scientific 
circles. Such an idea would certainly seem absurd, and 
yet this very strange fact has actually been discovered by 
astronomers. Phoebe moves round Saturn in a retrograde 
direction. Ultimately the satellite was caught by the 
telescope, but its luminosity is so feeble that there are 
probably only three or four telescopes existing powerful 
enough to detect it. 

Excellent photographs have been taken of the moon. 
At first it was usual to photograph the whole moon, but 
better results have been obtained by taking larger photo¬ 
graphs of different parts of our satellite. Recent photo¬ 
graphs seem to indicate that the moon is not yet quite 
dead; that there is still volcanic activity. One eminent 
astronomer believes that there is vegetation on the 
moon. 

By measuring the shadows cast by the mountains of the 
moon, it has been possible to calculate the height of these 
mountains, some of which appear to be covered with 
snow. Imagine making a complete map of a body which 
is distant two hundred and thirty-eight thousand miles 
from us ! Yet the maps of the moon which photography 
has enabled us to make contain every hill or valley that is 
one mile long and half a mile across. 

282 


PHOTOGRAPHING THE STARS 


We can only photograph one side of the moon, for she 
never turns round to let us see what the other side is like. 
The moon therefore performs a true waltz with our earth 
around the sun. Our earth, on the other hand, keeps 
continually turning around on its own account during the 
waltz. 

Another important part played by photography in our 
study of the heavenly bodies has been in connection with 
the sun, and more especially at times when our faithful 
moon has come between us and the sun, producing a total 
solar eclipse. 

The red flames or prominences seen during a total 
eclipse were proved to be appendages of the sun, for 
successive photographs showed the moon covering and un¬ 
covering these in her grand march past the sun. An idea 
had also existed that the beautiful corona seen around the 
disc of the moon at the time of total solar eclipse was an 
atmospheric effect, but two photographs of the corona 
taken almost simultaneously from two places many 
hundreds of miles distant from one another proved con¬ 
clusively that the corona had no connection with any 
interference of our atmosphere, but was an effect occur¬ 
ring at the sun. 

Photography has been of great service to astronomers 
in studying the nebulae , which had previously been a 
puzzle. These nebulae looked like far-distant clouds, or 
dull patches of light, and, indeed, were sometimes liable 
to be mistaken for comets. Photography discovered vast 
nebulae which had never been detected by the most 
powerful telescopes. 

These nebulae have turned out to be great masses of 
283 


PHOTOGRAPHING THE STARS 


incandescent gas. It has been impossible to say how far 
these vast bodies are distant from the earth, but there is 
evidence that they are at least as far off as the stars. 
Our whole solar system is a mere speck in the universe 
when compared with a great nebula. Each of these vast 
masses of incandescent gas may, in ages to come, be 
transformed into a star. We believe that every star 
commenced as a nebula. Who can say but some day, 
when our present photographs of nebulae become 
“ancient records,” the astronomers of ages to come may 
be able to point to these “ old charts ” as proof of the 
birth of some star known to them; the nebula in our 
photograph being the embryo or beginning of their star. 

When we consider our earth to be a mere speck com¬ 
pared with the sun, and when we think of the whole solar 
system as a mere dot compared with a great nebula, we 
become lost in wonderment. When we think of all the 
activity upon this earth, and when we consider the 
exquisite design in the tiny microscopic shells (illustration 
p. 216), we find it very difficult to place our whole world 
within a mere dot in the universe. It is none the less 
true that if some of the neighbouring planets were 
inhabited by intelligent beings, their astronomers would 
fail to discover our world with the best of telescopes. 
Indeed, unless it so happened that these inhabitants of 
another planet had acquired the art of photography and 
applied it to astronomy, they would never know of the 
presence of our planet in the universe. 

Perhaps the most interesting application of photography 
to astronomy is in connection with the spectroscope. 
While we find many of the sciences co-related, one would 
284 



Photos by Arthur E. Smith , London 

A Telephotograph 

The upper illustration is an ordinary photograph showing St. Alban’s Abbey in the 
distance. The lower illustration is a telephotograph taken from the very same 
position, one mile distant from the Abbey. The little frame in the upper illustration 
marks off the exact portion of that picture taken in by the telephoto lens in the 
lower illustration. (See chap, xviii.) 


















PHOTOGRAPHING THE STARS 

have thought that astronomy and chemistry must for 
ever stand apart. We cannot hope to get to the stars to 
find out their chemical composition, but the spectroscope 
has enabled us to find out the different elements present 
in the sun and other stars. 

In those earlier chapters which dealt with the subject 
of colour photography we considered the effect produced 
by passing light through a triangular glass prism. We 
saw that white light was analysed or split up into a 
spectrum of beautiful colours, commencing with red at 
one end and finishing with violet at the other end. In 
order to make the resulting spectrum as sharp and defined 
as possible, the light is passed through a narrow slot 
before it reaches the prism. In this way the overlapping 
of the bands of different colours is prevented, and we 
have what is called a pure spectrum. 

A simple spectroscope is therefore merely a glass prism 
and a shutter with a slot in it. Sometimes the shutter is 
mounted in a brass tube, and an arrangement made 
whereby the width of the slot may be altered at will. 
Then comes the glass prism, and another brass tube with 
an eyepiece, which is practically a small telescope to mag¬ 
nify the image of the spectrum. 

If our subject was the spectroscope, and not photo¬ 
graphy, we should want several chapters to deal with the 
subject. We must content ourselves with a few details, 
such as are necessary to a proper understanding of 
the part photography plays in connection with spec¬ 
troscopy. 

Before we can examine any substance by means of the 
spectroscope, the substance under examination must be 
285 


PHOTOGRAPHING THE STARS 


sending out light. The sun and the stars are therefore 
suitable objects for examination: but how are we to 
know what the different spectra mean ? Suppose we 
make a few simple experiments in the laboratory before 
attempting to photograph the spectra of the different 
stars. 

We wish to examine a piece of iron by the spectro¬ 
scope ; we must make it white-hot. On looking at it 
through the spectroscope we see a simple continuous 
spectrum, such as is got from white light. We try another 
solid body, and the result is just the same. Indeed, we 
find that all solid or liquid bodies, when made to in¬ 
candesce, give us a simple continuous spectrum . How, 
then, are we going to learn anything from the spectro¬ 
scope ? 

First let us see what appearance a burning or in¬ 
candescent gas has in the spectroscope. We burn a piece 
of sodium in a hot flame, say that of a bunsen burner. 
We at once see a very bright line in the yellow band of 
the spectrum. This bright yellow line always appeal’s in 
that position when sodium is in the form of an in¬ 
candescent gas. Hydrogen, when incandescent, gives a 
bright line in the red and a bright line in the blue. There 
are other lines seen with good apparatus, but these two 
lines are always particularly prominent. And so we find 
that every incandescent gas has definite bright lines. 

Suppose we are examining a sodium flame, and we see 
in the spectroscope a bright line in the yellow. While 
we are looking at this, some one makes a white light 
shine through the flame, by placing a white-hot solid body 
behind it. We immediately see a dark line in the yellow 
286 


PHOTOGRAPHING THE STARS 


band in the place of the former bright line. The sodium 
flame has absorbed certain rays from the white light 
passing through it, and so cut them off, leaving a blank 
in their place in the resulting spectrum. We may there¬ 
fore detect sodium by this dark line. This is what we 
have to do when examining the spectra of the heavenly 
bodies. The light from the distant star is passed 
through a spectroscope, and a record of the spectrum 
is made to impress itself upon a photographic plate. 
We find a great number of dark lines; the positions of 
these are carefully noted and compared with the different 
spectra which we can produce in the laboratory in the 
manner already indicated. A careful examination of a 
photograph of the spectrum of the sun shows us that 
hydrogen, sodium, iron, copper, nickel, zinc, etc., all 
exist in that great body which is ninety-three millions of 
miles distant from us. We are not to think of copper 
mines, etc., in the sun; what the spectroscope shows is 
that all these substances exist in the sun in a gaseous 
state. 

To-day many observatories are taking photographic 
records of the spectra of the different heavenly bodies. 
These records should be of great interest in the centuries 
to come. Future astronomers may compare our records 
with the spectra then obtainable, and thus note any 
alteration in the condition of the stars. 

Even in our own time, many interesting facts have 
been discovered by very carefully comparing the lines 
obtained in different photographs of the spectra of some 
distant stars. The lines of hydrogen, for instance, 
should appear in all photographs in exactly the same 
287 


PHOTOGRAPHING THE STARS 


position in the spectrum, no matter whether it be a 
distant star or a laboratory experiment which is being 
photographed. It was found, however, that there was 
a slight difference in the position of these lines in certain 
stars. Take, for instance, the star Sirius, the brightest 
in the heavens, and perhaps better known to some as 
the Dog Star. It was found that the lines representing 
hydrogen were very slightly nearer the red end of the 
spectrum than on the records made of other stars, and also 
of hydrogen burning in the laboratory. What could this 
mean P 

Have you ever been standing on a wayside railway 
platform when an express train was about to run through 
the station ? The whistle of the engine seems to rise in 
pitch as the train rushes towards you, and falls again to 
a lower note as the train passes away. Indeed, it has 
quite the effect of a syren, and yet we know that the 
whistle is sounding only one definite note. The whistle 
is setting up one definite rate of air vibration all the 
time; but as the train rushes towards you these air waves 
arrive, one after the other, quicker than they would if the 
engine was standing in one position. Hence a higher 
pitch of note. Imagine the whistle giving a definite 
number of blows to the atmosphere in a certain space of 
time. We then picture the sound wave set up by the 
first blow to be travelling towards us; but the engine 
darts forward as it gives the second blow. It is just as 
though the engine made up very slightly upon the first 
sound wave before it dealt the second blow, so that the 
air waves follow each other closer than they would other¬ 
wise do. They come tumbling against your ear in quicker 
288 


PHOTOGRAPHING THE STARS 

succession than they would do if the engine remained 
standing while it dealt out the blows. On the other hand, 
when the engine is rushing away from you, the vibrations 
or pulses are a little farther apart, the engine moving 
farther and farther away at each blow. 

Keeping this analogy before us, we note that the position 
of the dark lines really indicates the pitch of the different 
rays of light. If the rate of vibration be increased, the 
dark line will move nearer the violet end of the spectrum ; 
that is, “ up the scale.” If the rate of vibration be 
decreased, the line will move down the scale towards the 
red or lower end of the spectrum. Looking at the record 
of Sirius, we find the displacement is so small that it 
requires delicate apparatus to measure it. The displace¬ 
ment is towards the red end; the Dog Star is therefore 
receding from us. The amount of displacement in the 
spectrum indicates the rate at which this far-distant star 
is travelling. In the case of Sirius we find it is moving 
away from us about twenty miles every second. Other 
stars are receding at rates of from ten to thirty miles per 
second. One might be rather alarmed to learn that the 
spectrum photographs of some stars prove that they are 
approaching us at somewhat similar speeds. It will be 
apparent that there is no cause for panic when we con¬ 
sider that the nearest star to us is many billions of miles 
away, while some stars are distant thousands of billions of 
miles from our little globe. 

It is surely a very remarkable achievement to be able 
to tell whether a body, distant billions of miles from us, 
is approaching or receding from our earth! Why, if one 
stands on a long, straight road, it is difficult to tell 
T 289 


PHOTOGRAPHING THE STARS 


whether a distant tramway car is approaching or receding 
from us! 

There is another interesting astronomical discovery due 
to photography which I shall merely mention. Many 
spectrum photographs had been taken of one of the stars 
in the constellation known as The Great Bear . On some 
of these photographs it was found that one of the pro¬ 
minent lines in the spectrum was sometimes double, while 
in other photographs it was single. It was proved that 
this star must in reality be two separate bodies very close 
to each other. Photography therefore discovered the 
double star, which up till then passed itself off as a single 
star to all observers. The line was single in some photo¬ 
graphs, because at the time of taking such photographs 
the one star, revolving round the other, hid its twin 
brother from the eye of the camera. 

There is an amusing incident related by Sir William 
Abney in connection with spectrum photography. On 
one occasion this learned scientist was taking some photo¬ 
graphs of the sun’s spectrum from the summit of one of 
the Swiss Alps. He had travelled from England to get 
a clear atmosphere, and also to get a little nearer to the 
sun by climbing a high mountain. Of course, the actual 
difference in distance would make no appreciable difference, 
but by climbing to this height he would have less atmo¬ 
sphere between the sun and his camera-lens, which would 
be a distinct advantage. 

The particular object of study was to determine 
whether a certain group of lines in the photographic 
spectrum beyond the visible part might not be due to a 
hydro-carbon vapour. 


290 


PHOTOGRAPHING THE STARS 


While Sir William Abney was arranging his instru¬ 
ments, an American gentleman came upon the scene and 
watched the scientist with patient interest. After one 
hour of silent watching the American said, “ I guess, sir, 
you've got a photograph behind that." To this the 
scientist agreed. The American next exclaimed, “ Well, 
sir, what are you doing with the sun P" It flashed into 
the mind of the scientist that here was an opportunity of 
having some fun. Sodium, of which soda is one com¬ 
bination, had already been found in the spectrum of the 
sun; alcohol and brandy might be classed as carbo¬ 
hydrates along with the hydro-carbon vapour for which 
he was searching. With these thoughts in his mind the 
scientist gravely replied, “ Sir, we have already found 
soda in the sun, and now I am trying to find the brandy." 
The American made no further remark; he hurried down 
to Zermatt, and informed the people in the hotel that he 
had encountered a lunatic Englishman on the mountain. 
“ The poor fellow was trying to get a brandy and soda 
from the sun." 

In closing this chapter it may be of interest to add 
that one observatory (Harvard College) has taken as 
many as six thousand stellar photographs in one year. 
This indicates the important part which photography 
plays in connection with modern astronomy. 


291 


CHAPTER XX 


PHOTOGRAPHY AND SCIENCE 

Photographing sound waves—Photographs of flying bullets—Collision 
between two drops of water—The splash of a drop of water—The 
breaking of a soap-bubble—Ripple photography—A falling cat— 
Crossing waves—Photographing through Nature’s lenses—Fish-eye 
photography—Far-distant earthquakes photographically recorded 
—Other spot-light photographs—Is there such a thing as dark 
lightning ?—Cloud photography. 

T O speak of photographing sound waves in the air 
will doubtless seem quite ridiculous to the ordinary 
reader, and yet several scientists have accomplished 
this wonderful feat. 

I remember seeing quite a large collection of photo¬ 
graphs of air disturbances which were taken by H. Stanley 
Allen, at Lord Blythswood’s laboratory, in 1901. The 
method of taking these photographs was very ingenious, 
and the results were admirable from a scientific point of 
view, although the man-in-the-street would have failed to 
see their value; there was nothing picturesque about 
them. 

The general reader would appreciate more readily the 
photographs taken by Professor C. V. Boys, where air 
waves are distinctly seen around flying bullets. A collec¬ 
tion of these photographs is to be found in the Physics 
Department of the South Kensington Museum (London). 
The general effect in a photograph of the flying bullet is 
292 


PHOTOGRAPHY AND SCIENCE 


very much the same as that of a steamer ploughing its 
way through the sea. Both the waves which spread out 
from the bow, and the disturbance or “ wake ” which 
follows in the trail of the steamer, are well represented in 
some photographs of a simple flying bullet. In other 
photographs the air waves are seen reflected from a sheet 
of metal placed in their path, and their behaviour is 
exactly like waves in water. But how did Professor Boys 
manage to photograph flying bullets ? 

To attempt to photograph a flying bullet by means of 
the very best of instantaneous shutters would be abso¬ 
lutely useless. We may take a snapshot of a train going 
at an express speed of sixty miles per hour, but the bullet 
is travelling at a speed of one thousand four hundred 
miles per hour. A momentary flare of flash-light powder 
is good enough to obtain a picture of a crowd of people 
assembled together, but quite useless in the case of a 
flying bullet. During the sudden flash of light the bullet 
would have passed with lightning speed across the area 
covered by the photographic plate. It is obvious that 
the illumination must be very short indeed before we can 
catch the image of a flying bullet. It goes so fast that 
we are unable to see it in its flight. Where are we to get 
an illumination sudden enough for the purpose ? 

An electric spark will give an illumination of the 
shortest possible duration. It has been calculated that 
some electric sparks occupy less than the one millionth 
part of a second. But all electric sparks are not of the 
same duration. Indeed, Professor Boys found that the 
first kind of electric sparks which he tried were far too 
slow to photograph the bullet shot from a magazine 
293 


PHOTOGRAPHY AND SCIENCE 


rifle. Daring the fraction of a second in which the 
spark existed, the bullet had travelled half an inch 
across his photographic plate. By adjusting the electric 
apparatus he was able to get sparks of so short duration 
that the flying bullets appeared in the photographs as 
though they were quite stationary in mid-air. But how 
is the photographer to snap his picture at the right 
moment ? He wishes to have the image of the bullet 
right on the centre of his photographic plate, but the 
whole time during which the bullet is within the compass 
of his camera cannot exceed the one two-hundredth part 
of a second. It is quite evident that the photographer 
cannot “ press the button 11 at the required moment. The 
bullet itself must operate the electric spark. 

We need not trouble with the detail of the electrical 
apparatus further than to note how the spark is timed. 
A spark-gap is arranged in such a manner that a spark 
occurring at this point will illuminate the whole area 
covered by the camera. An electric charge is waiting 
ready to spark across this gap, but it cannot do so be¬ 
cause of another small gap in one of the connecting 
wires. The moment that this second gap is bridged over 
by a piece of metal the discharge takes place, causing a 
spark at the desired point. Let the bullet itself be the 
piece of metal to bridge the gap in the connecting wire. 
This wire-gap may be arranged so that it forms the bull’s- 
eye to be aimed at. The instant that the bullet fills this 
gap the electric discharge takes place across the illuminat¬ 
ing spark-gap, and this all happens so very suddenly 
that a good snapshot photograph is obtained of the 
flying bullet. 


294 


PHOTOGRAPHY AND SCIENCE 


An interesting series of such photographs was taken 
of a bullet piercing a sheet of plate-glass. A photo¬ 
graph of the bullet was taken just entering the glass, and 
this showed a cloud of glass dust thrown backwards in 
the opposite direction to that in which the bullet was 
travelling. Another photograph of the bullet was taken 
after it had reached a distance of five inches beyond the 
sheet of glass. This showed the bullet completely enve¬ 
loped in a thick cluster of glass dust, giving the bullet 
the appearance of a long brush; the five-inch space 
between the bullet and the hole in the plate-glass being 
also filled with a mass of glass dust. 

Another photograph which Professor Boys took when 
the missile had reached a distance of fifteen inches be¬ 
yond the glass showed the bullet quite clear of the glass 
dust, but close to the bullet there was a single piece of 
glass, which, no doubt, was the piece immediately struck 
and punched out by the bullet. This piece of glass is 
seen to be travelling along by itself at a speed practically 
equal to that of the bullet. This small piece of glass is 
seen to be causing air waves on its own account. The air 
waves in all these photographs might be mistaken by a 
casual observer for cracks on the negative. 

These experiments ingeniously carried out by Professor 
Boys were suggested by some similar experiments made 
by Professor E. Mach, of Prague. The method of 
obtaining the photographs was considerably modified by 
Professor Boys. 

Professor Boys also took some interesting electric-spark 
photographs of a fine column of water falling from a jet. 
At first the water looked like a rope or cylinder, and then 
295 


PHOTOGRAPHY AND SCIENCE 


it began to bulge out at intervals, leaving a narrow neck 
between each pair of beads. At last these beads were 
seen to separate into little drops quite separate from one 
another. The same scientist photographed two drops of 
water in the act of bouncing against one another. The 
drops were flattened as they met, and behaved just as 
though they were india-rubber balls. 

Professor Worthington took a series of electric-spark 
photographs of a drop of water falling into milk. One 
photograph was taken just as the drop of water struck 
the surface of the milk, and this showed quite a cavity in 
the surface. Then one of the succeeding photographs 
showed quite a tall pillar of milk in the place where an 
instant before there was a hole. This effect was caused 
by the milk rushing in to fill the cavity, and in so doing 
the high pillar was momentarily formed. But for the 
testimony of the photographic plate we could not know 
that this strange result really happened during the splash 
of a drop of water. 

Lord Rayleigh took some very interesting electric-spark 
photographs of a soap-bubble in the act of breaking. In 
these photographs the retreating edge of the bubble, as 
it broke, is seen with all the accuracy and sharpness of 
a stationary object. 

Some interesting facts concerning ripples on the surface 
of liquids were determined by Dr. J. H. Vincent, by means 
of electric-spark photography. This scientist caused dif¬ 
ferent sets of ripples to be set up simultaneously on the 
surface of mercury, by means of two points attached to 
vibrating tuning-forks. The electric-spark photographs 
showed many interesting phenomena which could not be 
296 


PHOTOGRAPHY AND SCIENCE 


seen by the eye, owing to the rapidity with which they 
occurred. 

Some of the phenomena met with in the study of 
Sound and Light, such as reflection, interference, and 
refraction, have been well illustrated by this means. 
Some of these ripple photographs may be seen in the 
Physics Department of the South Kensington Museum 
(London). 

I have already referred, in an earlier chapter, to the 
electric-spark photographs taken of a flying insect. It is 
interesting to note that another experimenter made a series 
of such photographs of a cat falling from a height. The 
idea was to show how a cat was able to turn round in the 
air and land on her feet upon the ground. I understand 
that from a pictorial point of view the photographs were 
not very successful; the reason given being that the 
subjects did not care for this form of scientific investiga¬ 
tion. No doubt the experimenter would have difficulty 
in obtaining sufficient illumination to get all the detail of 
a falling cat. 

In the illustrations facing page 298 we have two very 
interesting photographs of wave effects, taken by Dr. 
Vaughan Cornish. The upper illustration shows two 
waves crossing each other almost at right angles and 
each continuing on its own way. Dr. Cornish has kindly 
given me the following particulars :— 

“The intention of the photograph is to illustrate a 
fundamental property of waves, namely, their interpene¬ 
tration and subsequent continuance each in its original 
course. It required six months’ waiting to obtain it. The 
297 


PHOTOGRAPHY AND SCIENCE 


photograph was taken with a No. 1 binocular camera, 
pointed downwards, the centre of the picture being about 
twelve feet distant. The photographer stood in the water, 
which had a depth of only two or three inches, upon a 
sandy shoal. The occasion was low water of a spring 
tide, and the locality the sandy shore opposite Branksome 
Chine, near Bournemouth (England). The weather was 
calm, and the ordinary waves, coming in from the offing 
and breaking some distance out, gave rise to small solitary 
waves foaming at the front. 

“ At first the solitary wave leaves the foam behind, but 
as the water becomes shallower, and the speed of the wave 
is thereby reduced, the foam which it makes travels with 
it and becomes a roll of opaque white froth which out¬ 
lines the wave-front with great distinctness, and gives the 
photographer his opportunity. 

“At the moment when this photograph was taken a 
‘solitary 1 wave, deflected from the shore and travelling 
seawards over the sandy shoal, met the next incoming 
wave at a spot which was brought to the centre of the 
camera’s field of view. Below this, in the photograph, 
the waves had previously met and passed through each 
other, each pursuing its original course. The line of 
momentary interference is recorded by an irregular band 
of foam. On either side of this the waves are seen to be 
pursuing each its original course. The increased ampli¬ 
tude of the momentarily combined wave is clearly shown 
at the point of intersection.” 

I may remark that this photograph attracted a good 
deal of attention at the St. Louis Exhibition (U.S.A.), 
and it was one of the photographs selected by the Royal 
298 



By permission op Dr. Vaughan Cornish 

Photography of Waves 


The upper illustration shows two waves crossing each other, and each continuing on 
its own way. It took six months’ waiting to obtain this photograph. The lower 
photograph shows sand waves produced by currents. (See chap, xx.) 


























I 














































PHOTOGRAPHY AND SCIENCE 


Commission for the souvenir volume of the British 
Exhibit. 1 

The lower illustration (p. 298) i-s a photograph taken 
in the Dovey Estuary, North Wales, and shows sand waves 
produced by currents. This photograph is of scientific 
value, and by request Dr. Vaughan Cornish has given a 
copy of it for preservation at the Geographical Society of 
Berlin. The full title given to the photograph is “ Cur¬ 
rent mark and tidal sand waves. ,1 


When considering Nature's camera , I incidentally re¬ 
marked that the eye of a particular species of beetle 
produced as many as twenty-five thousand images of the 
object which it was viewing. The experimental proof of 
this is very difficult to carry out. It is indeed remark¬ 
able that any one can dissect the head of a beetle so as to 
remove the eye without injury. The retina and the dark 
pigment interlining the eye have to be very carefully 
removed with a fine camel-hair brush, and the miniature 
transparent lens has to be placed in proper position in 
front of the objective of a powerful microscope. 

Having got the tiny lens, the microscope, and the 
camera in position, the scientist then takes a glass trans¬ 
parency, say a photograph of a man, and he places this 

1 The binocular camera mentioned by Dr. Cornish in connection 
with this photograph of crossing waves is rather like an opera glass 
in appearance. One half of the instrument is a camera and the other 
half is practically one eyepiece of an opera glass. The photographer 
holds the instrument up to his eyes, as he would hold an opera glass, 
and this he does while he is in the act of taking the instantaneous 
photograph. In this way the photographer was able to bring the 
image of the crossing waves fairly on to the centre of his sensitive 
film. 


299 


PHOTOGRAPHY AND SCIENCE 


so that a strong image of it is reflected on to the tiny 
lens, or in other words, the eye of the beetle. The micro¬ 
scope enlarges the manifold image formed by the insect’s 
eye, and a photograph is taken of the enlarged image 
produced by the microscope. It will be obvious that it 
would be quite impossible to observe the manifold image 
produced by the beetle’s eye except with a microscope, as 
the whole area of the eye is a mere speck, and in this 
space there are twenty-five thousand distinct images. Of 
course, one cannot hope to make the whole of these 
images simultaneously visible in one photo-micrograph, 
the necessary magnification being so great that only a 
portion of the whole can be brought within the micro¬ 
scope lens at one time. In a photo-micrograph measuring 
one and three-quarter inches by two and a half inches I 
have counted as many as one hundred distinct images, 
each image being an exact duplicate of the other. 

An Austrian professor, anxious to see what an insect 
really sees, arranged his apparatus in a similar manner to 
that just described, but instead of throwing the image of 
a photograph upon the insect’s eye, he allowed an image 
of the view obtained from his window to fall directly on 
the little lens. In this experiment the eye of a firefly 
was used so that a larger picture might be produced, not 
by any increase in the size of the tiny eye, but because 
this insect’s eye does not produce manifold images, as in 
the previous case. Quite a good photograph of the 
window, with a church in the distance, was obtained by 
this means. 

With such very small lenses as those from the eye of 
a beetle or a firefly it is necessary to take the photo- 

300 


PHOTOGRAPHY AND SCIENCE 


graphs through a microscope, but experiments have been 
made with some of Nature’s larger lenses, allowing the 
microscope to be dispensed with. The crystalline lens 
taken from the eye of a freshly killed bullock has been 
used in place of the ordinary camera lens. Very great 
care is required in handling this natural lens, but the 
results obtained, in some cases, have been excellent. 

A totally different series of experiments was made by 
Professor Wood (U.S.A.), and described by him in the 
Philosophical Magazine of August, 1906, under the title 
of “ Fish Eye Views.’ 1 

In the illustrations opposite page 254 we saw how light 
was bent in passing from the air into water. Imagine the 
penny in these photographs to be the eye of a fish which is 
swimming in the basin. It is obvious that the fish would 
have a very wide range of vision, the light being bent 
over the top of the basin at every point around its cir¬ 
cumference. Therefore a fish placed at the centre of a 
small pond of clear water must have a very wide view of 
the objects surrounding the pond. 

It is difficult to make personal experiments; our eyes 
are not adapted to distinct vision under water. It is well 
known, however, that if one looks upwards from beneath 
still water one sees the sky compressed into a compara¬ 
tively small circle of light, the centre of which is always 
immediately above the observer. It just looks as if the 
whole pond were covered with a dark roof, with a circular 
window in its centre. As already stated, it is difficult to 
distinguish any objects that are out of the water. 

It occurred to Professor Wood that an excellent notion 
of how we appear to the fishes could be obtained by im- 
301 


PHOTOGRAPHY AND SCIENCE 


mersing a camera in water and photographing the circle 
of light above it. 

The apparatus was constructed out of a lard pail and 
a short focus lens provided with a diaphragm having a 
very small aperture in it. The lens and its diaphragm 
were fitted into a metal disc, which rested on a metal rim 
soldered around the inside of the pail, about midway 
between the bottom and the mouth of the pail. The lower 
half of the pail was therefore to act as the camera or 
imitation fish’s eye. This part of the pail was filled with 
clear water after the photographic plate had been placed 
in position on the bottom of the pail. This operation 
was necessarily performed in a dark room. Then the 
upper part of the pail was also filled with water, so that 
this part of the pail represented a miniature pond. The 
lens of the submerged camera was covered with a metal 
cap, keeping the dark chamber light-proof. This shutter 
was provided with a handle on the outside of the pail, 
enabling the shutter to be opened and closed at will. 

This miniature pond with its submerged camera was 
then placed upon the ground, and a number of extremely 
interesting photographs were obtained with this device. 
A number of men standing around the miniature pond 
were seen in the photograph in a somewhat distorted condi¬ 
tion, and this must be the idea a fish gets of us when we 
look into the small pond or river in which he is swimming. 

By modifying the apparatus so that it could be held in 
a horizontal position, one could make the camera “ look ” 
along instead of upwards. In this position the camera 
takes the place of the eye of a fish looking out through 
the glass sides of an aquarium. Some very curious 
302 


PHOTOGRAPHY AND SCIENCE 


photographs were taken in this manner. Again, the fish 
has a very wide range of view. 

If a straight row of nine men were to stand close up 
to the side of the glass aquarium, the fish would see the 
whole row of them, but not in a straight line. They 
would appear to be standing in a large semicircle, with 
their backs to the centre of the circle. The men at the 
ends of the row would appear to be away out about the 
centre of the room instead of being in a straight line 
with the fish’s domain. 

It will be understood that Professor Wood was not 
experimenting with the eye of a fish, but with a photo¬ 
graphic apparatus made to imitate the fish’s eye. In 
the experiments described immediately before these, the 
actual eyes of beetles, etc., were used to focus the images 
for the camera. 

Photography is of great service to science quite apart 
from the pictorial aspect. The movements of a spot of 
light may record themselves upon a photographic paper, 
and by keeping a sensitised paper ribbon in regular 
processional motion, a spot of light falling upon it will 
leave a continuous record of all its movements. 

One interesting application of this fact is in automati¬ 
cally recording far-distant earthquakes. It may seem 
quite ridiculous to attempt to record the altogether 
imperceptible tremors caused in Great Britain by earth¬ 
quakes occurring in India, Siberia, or Japan. We are 
totally unconscious of any such tremors, but our photo¬ 
graphic paper will inform us of their occurrence. 

In the British Observatory we dig a deep pit until we 
3°3 


PHOTOGRAPHY AND SCIENCE 


get down twenty or thirty feet below the surface. We 
then erect a solid pier or pillar of masonry upon this deep 
foundation. The top of this pier pops up in the observa¬ 
tory, through a hole in the floor, and is used as a small 
table upon which the earthquake apparatus, or seismo¬ 
graph, stands. The instrument is therefore quite safe 
from all local surface disturbances. 

The instrument consists of a long boom, which is so 
very light and so delicately poised that it will move with 
the very slightest tremor of the earth. This boom, 
which is made of aluminium, will merely oscillate from 
left to right, the total distance of its to-and-fro vibration 
being very small. It must be obvious that there is no use 
in attempting to record the movements of this boom by 
attaching a pen or other marker to it. Any such arrange¬ 
ment would immediately arrest the movement of the 
boom. It is here that photography steps in to aid the 
scientist. 

The end of the boom carries a very light plate or 
shutter of aluminium, in the centre of which is a longi¬ 
tudinal slot, while there is above this a lateral slot in 
the mahogany case which encloses the apparatus. The 
light of a lamp passing through the intersection of these 
slots causes a spot of light to fall upon the ribbon of 
photographic paper, which is kept in continuous and 
regular motion by clockwork. When the boom is at rest 
the spot of light makes a black line along the centre of 
the paper ribbon, while some light gets past the edges 
of the shutter and makes a black border on either edge of 
the ribbon. The very slightest movement of the earth 
causes the boom to vibrate, thus making the centre line 
304 


PHOTOGRAPHY AND SCIENCE 


wavy and the outer edges irregular, as shown in the 
accompanying illustration (Fig. D). 

This is a reproduction of a photographic record taken 
in the Coats’ Observatory at Paisley (Scotland), and the 
earthquake, which directly moved the instrument occurred 
in far-distant Shemakha (Russia). 

While the photographic record shows the hour and the 
duration of the earthquake, it cannot give any indication 
of the part of the world in which the disturbance has 



Fig. D 


occurred. The earthquake may be recorded here several 
days previous to any information reaching us as to its 
whereabouts, especially if the disturbance is in some out- 
of-the-world place, where all means of telegraphic com¬ 
munication may have broken down. 

In those observatories where magnetic observations are 
taken it used to be a very laborious task to note the varia¬ 
tions in the directions of the earth’s magnetism. A large 
magnet, measuring about two feet in length, if suspended 
by a long silk thread, will not point steadily to the mag¬ 
netic north pole of the earth all day long. It will move 
slightly to the west between eight o’clock in the morning 
305 


u 









PHOTOGRAPHY AND SCIENCE 


and two o’clock in the afternoon, and then slowly return 
eastwards. During the night there is practically no 
movement. As the total movement from west to east is 
only about the thirtieth part of an inch at the end of a 
magnet measuring two feet, it is obvious that it will not 
concern the mariner. There is, however, a scientific in¬ 
terest attached to these small variations, which are 
irregular. During some years the average amount of 
movement is double that of other years. It is always 
greater in summer than in winter. 

The reading of the exact position of the long magnet 
was a tedious and a delicate task, which had to be per¬ 
formed twelve times every day. Photography stepped in 
and relieved the observer of his arduous duty. A small 
mirror attached to the magnet reflects a beam of light 
directed upon it, and thus throws a spot of light upon a 
photographic paper. This band of sensitised paper is 
moved by clockwork, just as in the earthquake apparatus, 
so that it keeps a continuous record, marked off in hours, 
of the position of the magnet. The observer therefore 
obtains a photographic chart showing exactly how far the 
magnet has wandered from the magnetic north pole. 

The photographic spot of light serves the scientist in 
very many different ways, but the two cases just described 
will give the reader an idea of this kind of work. 

Two Austrian inventors have used a spot of light to 
write down telegraph messages in ordinary writing upon 
a sheet of photographic paper. The one great advantage 
is that the pencil of light may be made to move very 
rapidly, so that an extraordinarily high speed has been 
attained. The spot of light is reflected by a little mirror, 
306 


PHOTOGRAPHY AND SCIENCE 


the movements of which are controlled by the electric 
current. The spot of light dances about on the sensitised 
paper, reminding one of the fairy light “Tinker-Bell, 1 ’ 
in J. M. Barrie’s Peter Pan. 

All the photographic records of the movements of 
a spot of light are made upon a bromide emulsion paper, 
and therefore the record is not visible until the paper is 
chemically developed. In the case of this high-speed 
telegraph, the apparatus automatically develops the record, 
so that the telegram is complete when taken from the 
machine. 

In the lower illustration, facing page 308, we see the 
photograph of an apparent dark flash of lightning, and 
in the legend beneath this illustration I have asked the 
question—“ Is there such a thing as dark lightning ? ” 
Scientists could not definitely answer this question at one 
time, but Dr. W. J. S. Lockyer, of the Solar Physics 
Observatory (London), has helped to make matters quite 
clear. 

It had been suggested by one writer that the apparent 
dark flash was produced in the following way. A bright 
flash having occurred and made an impression upon the 
photographic plate, another flash follows sufficiently near 
to the first to illuminate the plate, whereupon the first 
image will appear dark instead of bright, when the plate 
is developed. 

Dr. Lockyer secured photographs of quite a variety 
of dark flashes of lightning, and he then proceeded to 
imitate the results by means of electric discharges in the 
laboratory. 


307 


PHOTOGRAPHY AND SCIENCE 


If we look carefully at the dark flash in the photo¬ 
graph, we shall see that there is a bright core along 
the centre of the dark flash. Dr. Lockyer was able to 
produce the same effect by means of electric sparks 
in the laboratory. His experiments quite confirmed 
the suggested theory of the dark flashes being due to 
a second illumination of the plate. 

Taking first of all a photograph of a single spark, he 
developed the plate and found that it represented a 
bright flash. Repeating the experiment, but leaving the 
sensitive plate still in the camera, he moved his sparking 
apparatus very slightly, so that the image of a second 
spark would fall clear of the first impression. He then 
caused two sparks to pass in succession, and again four 
sparks on another part of the plate. The first and second 
sparks were found to be dark flashes with bright cores, 
just like the dark lightning in our illustration. The last 
spark alone appeared as a bright flash. By varying the 
intensity of the sparks, and that of the illuminated back¬ 
ground, it was found possible to produce any combination 
of bright and dark flashes. 

It is therefore quite clear that there is no such thing 
as dark lightning in nature. Every lightning discharge, 
if photographed and immediately protected from a second 
flash, will show a bright flash upon development. The 
dark flash is only seen upon a photographic plate which 
has been illuminated after the first impression was 
made. The apparent dark flash is therefore due to some 
chemical action which takes place in the photographic 
film. 

Immediately above the photograph of the dark light- 
308 



By permission oj Dr. IV. y. S. I.ockyer, 

Solar Physics Observatory 

A Cloud and Dark LicxHtning 

The upper illustration is a study of the formation of a cloud. The lower illustration 
shows an apparent dark flash of lightning. Is there such a thing as dark lightning? 

(See chap, xx.) 










































































































































* 













PHOTOGRAPHY AND SCIENCE 


ning is a beautiful photograph of a cumulus cloud. 
Cloud photographs are taken for two quite different 
purposes. The object in this case has been to show the 
formation of the cloud. It is most interesting to have 
a series of photographs of a cloud, taken at intervals 
of a minute between each successive picture. In this 
way one can see exactly how the cloud changes from one 
shape to another totally different formation. 

The second object in cloud photography is to secure 
cloud negatives which may be used along with other 
photographs. For instance, one may have a good land¬ 
scape photograph, but the sky has nothing of interest in 
it. If one prints in some clouds from a suitable negative, 
the general effect of the landscape is greatly enhanced. 

We have already seen, in some of the other chapters, 
many ways in which photography aids the scientist. Not 
only in the study of the invisible part of the spectrum, 
and other invisible rays such as those emitted by radium 
and other radio-active bodies, but also in a study of 
bacteria and other objects far below the range of vision. 
In another chapter we saw how photography aided the 
astronomer, and so on. With what has been added in this 
chapter it must be clear that photography plays a very 
important part in scientific research. 


309 


CHAPTER XXI 


A CAMERA WITHOUT A LENS, &c. 


.The pinhole camera—The disadvantages 'of lensless photography— 
Why we use lenses in the camera—The making of photographic 
lenses—Some curious points about lenses—Wherein the expense 
lies—Lenses for different purposes—What determines the focus of 
a lens?—Early suggestion of a portrait lens—How the lens bends 
the rays of light—Is the obtaining of a good lens a matter of 
chance?—How the form of a lens is first determined* 

A FTER the reader has examined the illustrations, 
shown facing page 316, and when he learns that 
these beautiful pictures were taken through a simple 
pinhole, he may be inclined to ask why we should bother 
about using a lens at all. 

It is certainly remarkable that such excellent results 
may be obtained, with no apparatus other than a dark 
box with a pinhole aperture in it. It will be obvious, 
however, that there must be some advantages to be gained 
by the use of lenses, otherwise the photographer would 
not pay anything from a guinea to one hundred and fifty 
guineas for a good lens. 

Let us first of all see wherein lie the disadvantages of 
a camera without a lens. We cannot say anything 
against lack of definition in the two illustrations, but if 
we were to photograph some large object from a short 
distance, we should then find a want of sharpness about 
the picture. Before we could have a pinhole that would 
310 


A CAMERA WITHOUT A LENS, &c. 

focus with perfect sharpness, the hole would require to be 
so small that it would allow only one ray of light from 
each point of the object to enter the camera. And the 
material in which this ideally small hole is to be made 
must have no thickness whatever. Neither of these con¬ 
ditions can be fulfilled, but by drilling a very small hole 
in a sheet of very thin brass or tinfoil very beautiful 
pictures may be produced. This fact is admirably borne 
out by the two photographs reproduced in the illustra¬ 
tion. These photographs were taken by the Rev. J. B. 
Thomson, of Greenock, who is an authority on the subject 
of pinhole photography. 

I think that, as far as landscapes are concerned, no one 
will find fault with the productions of lensless photo¬ 
graphy. Indeed, a lens sometimes produces an unreal 
effect in a photograph by giving too good a focus. In 
other words, the lens of the camera may bring the rays 
of light to a sharper focus than the crystalline lenses of 
our eyes do in ordinary vision. In modern photographic 
exhibitions one sees many pictures which have been taken 
with the lenses purposely out of focus in order to produce 
a more realistic effect. 

One is not surprised to learn that it would be quite 
impossible to focus the pinhole picture upon a ground 
glass focussing screen ; there is so very little light admitted 
to the camera that one cannot see the image. Fortu¬ 
nately there is no need of any focussing. No matter at 
what distance one places the photographic film from the 
pinhole, the image is always in focus. Of course, the 
farther away one places the sensitised film the larger will 
the image be. 

311 


A CAMERA WITHOUT A LENS, &c. 


There is another interesting point about pinhole pho¬ 
tography, and this is a point in its favour. The defini¬ 
tion of the picture is equally good for all objects, no 
matter at what distance they are away. This sentence 
may seem somewhat to contradict an earlier statement, 
in which I said that if one had a pinhole photograph of 
a large object taken from a short distance, one would see 
that there was a want of sharpness about the picture. 
There is really no contradiction. We do not notice the 
lack of definition in the distant landscape, but we should 
observe it in a large image of some detailed object. 

This evenness of definition for all distances is practically 
perfect in lensless photography, while it is otherwise 
with lenses. Both the foreground and the background 
are often far out of focus. 

Wherein, then, does the real disadvantage in lensless 
photography lie ? The answer to this question must be 
obvious, for if one thinks of the total amount of light 
which can enter the camera through a pinhole, it must be 
clear that a very long exposure will be necessary to enable 
the faint image to affect the chemicals upon the photo¬ 
graphic film. There is no use in attempting to increase 
the size of the hole; we should certainly admit more 
light, but the resulting image would be blurred. In¬ 
deed, if we made the hole large enough to admit a 
good light, we should find that no image at all would 
appear. 

How long, then, does a pinhole exposure require to be ? 
A fair idea of the exposure required may be gathered 
from the general statement that a pinhole photograph 
requires as many minutes as it would take seconds by an 
312 


A CAMERA WITHOUT A LENS, &c. 

ordinary camera with a lens. Accordingly a picture 
which could be taken by an ordinary camera in one 
minute, would require an hour’s exposure with a pinhole 
camera under the same conditions. 

The chief purpose of a lens, therefore, is to admit 
more light into the camera, and still bring the image to a 
focus. The old-time Italian philosopher, Battista Porta, 
found that the pictures in his camera obscura were greatly 
improved when he placed a lens at the hole in his 
shutter. 

It will be obvious that the more light a lens can pass 
into a camera the better will it be for instantaneous pho¬ 
tography. Hence we hear of rapid or instantaneous 
lenses. 

As we are not considering the subject from a practical 
standpoint, we need not trouble ourselves with the par¬ 
ticular forms of lenses required for different purposes. It 
will be of more general interest to form some idea of the 
method of making photographic lenses. 

It goes without saying that the lenses are made of 
glass, although there have been such things as liquid 
lenses. We all appreciate the light-transmitting quali¬ 
ties of glass, and none of us would care to return to the 
fourteenth-century open lattices or windows of oiled paper. 

Most of us have some idea of the manner in which 
glass is made. Certain raw materials are mixed together 
and practically boiled in hot furnaces. Indeed, the whole 
process is not unlike the making of toffee, in which the 
ingredients, at certain stages, require to be stirred with a 
ladle. 

If the raw materials used are compounds of sand, potash, 
3i3 


A CAMERA WITHOUT A LENS, &c. 


and lead, then the resultant mixture is termed flint glass. 
If, on the other hand, the mixture is sand, soda, and lime, 
it is known as crown glass. Both flint and crown glass 
are used in the making of photographic lenses. A de¬ 
mand for finer work produced modifications of these. 
The new kinds of glass were first made in some works 
at Jena, in Germany, so that they are known as Jena 
glasses. These glasses are made by adding other in¬ 
gredients, such as phosphorus, aluminium, etc., to the 
mixtures which are to be boiled. 

One interesting point in the manufacture of glass 
is the method of obtaining a regular density through¬ 
out the mass. If the glass were more compressed in 
one part than another, the power of bending the rays 
of light would vary accordingly in different parts of the 
glass. The glass-maker meets with a troublesome diffi¬ 
culty here, for if he withdraws his glass from the furnace, 
the outside of the mass will cool more quickly than 
the inner portion. This cooling of the outside will cause 
a greater pressure upon the inside portion, so that it will 
become more dense. What can the glass-maker do to 
obviate this serious fault ? He must cool the glass very 
gradually by means of ovens, in which he can bring the 
temperature very gradually down. The whole mass will 
then cool equally, and the process is called annealing. 
Large discs of glass may require many weeks during 
which they are gradually cooled. 

Some of the glasses which are most suitable for photo¬ 
graphic lenses are necessarily of a soft nature, owing to 
their composition. They are therefore much more easily 
scratched than is ordinary glass; hence the care required 
3M 


A CAMERA WITHOUT A LENS, &c. 

in cleaning fine photographic lenses. It is a curious fact 
that these glass lenses are somewhat elastic. Indeed, if 
the lens-maker is not very careful in mounting a fine lens 
in its metal socket or cell, he may spoil the focus of the 
lens by making the cell press too tightly upon the edge 
of the lens. 

Another curious point about some kinds of glasses is 
that they tarnish on exposure to air just as easily as iron 
rusts. When the lens-maker uses this kind of glass, he 
must protect it from the air by enclosing it between lenses 
made from another glass which will not tarnish. 

If lenses could be cast in moulds, in the same way as 
glass ornaments, the prices would be very different from 
what they are, but, unfortunately, this cannot be. A 
block of glass has to be cut and then ground down to the 
required shape. In grinding, the glass is rubbed against 
a hard metal tool, or mould, of the desired shape, while 
emery, sand, or diamond dust, is placed between the sur¬ 
face of the glass and the tool. The glass is caused to 
assume gradually the shape of the tool. 

For simple lenses, such as are used in spectacles, and for 
cheap lenses, this process of grinding may be deputed to 
automatic machines. Photographic lenses, however, not 
only require skilled labour, but the making of fine lenses 
can only be accomplished by a certain delicacy of touch 
upon the part of the operator. 

After the lens has been ground to the desired shape it 
requires to be polished to remove the marks of grinding. 
The polishing is very similar to the grinding process, 
except that rouge powder is used in place of the emery, 
and a mould or tool having a softer surface, such as cloth 
3i5 


A CAMERA WITHOUT A LENS, &c. 

or wax, replaces the hard metal tool. By this means the 
lens is given a lustrous “ black ” polish. An imperfect 
polish will scatter the light into the camera, and this will 
be detrimental to the image. 

The great delicacy of the work necessary in making fine 
lenses may be appreciated when we learn that before the 
operator can measure the results he has produced in the 
lens he must let the lens cool down to a perfectly even 
temperature. The curvature of the lens will alter with 
an unequal temperature. 

Modern photographic lenses are made up of a combina¬ 
tion of several different lenses, and are fitted together like 
a short telescope. As already indicated, the forms of 
these vary greatly according to the particular purpose for 
which they are intended. We find lenses described as 
portrait, view, rapid-landscape, wide-angle, tele-photo, 
universal, etc. 

One point of interest is that the focus of a lens—its 
focal length—is not dependent alone upon the shape or 
curvature of the lens. The composition of the glass has 
a great deal to do with determining the focus. Two 
lenses of exactly the same form may bend the rays of 
light in different degrees. If the two lenses are made of 
different kinds of glass, the one may bring the rays to a 
focus at three inches from the lens, whereas the other’s 
focal length may be six inches. 

There is another interesting point in connection with 
photographic lenses, and this was observed at a very early 
date in the history of photography. In the Philosophical 
Magazine of October, 1839, there is a letter addressed to 
the editors by Dr. John T. Towson, and entitled “ On the 
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A CAMERA WITHOUT A LENS, &c. 

Proper Focus for the Daguerreotype.” In this letter the 
writer points out that lenses, as then known, did not bring 
the chemical rays of light to a focus at the same point as 
the visible or luminous rays. Therefore, when Daguerre 
focussed his picture on the ground-glass screen, he was 
not finding the true focus of the chief rays which affected 
his photographic plate. The picture would appear in 
good focus upon the screen, but the “invisible image” 
formed by the chemical rays would be out of focus, and 
the resulting picture would therefore be in the same con¬ 
dition. The yellow rays of light produce the greater 
part of the illumination, and it is well known that these 
yellow rays have practically nothing to do with the pro¬ 
duction of the picture, as is shown by the use of a yellow 
lamp in the dark room. 

In his letter, Dr. Towson goes on to ask how Daguerre 
succeeds in producing such good results, and the writer 
explains it in this way. He points out that Daguerre 
“ stops down ” his lens, so that light only passes through 
a small portion at the centre of it. In this way only the 
rays which require least bending are allowed to enter the 
camera, or, in other words, only the light which is making 
a fairly straight course for the photographic plate gets in. 
Those rays which strike the lens at a considerable angle 
and would therefore require to be greatly bent are not 
accepted, for the greater the bending which takes place 
the more exaggerated will be the difference of focus 
between the visible and the chemical rays. The reader 
is not to imagine that none of the visible rays take part 
in the making of a photograph; but this subject will fall 
better within the title of the following chapter. 

3D 


A CAMERA WITHOUT A LENS, &c. 


This closing up of the greater part of the lens by 
Daguerre, necessarily meant a long exposure, and there¬ 
fore Dr. Towson proposed that a large lens might be used 
if it was corrected so as to bring all the rays of light to 
one and the same focus. The particular object in view 
was the possibility of taking portraits from life, so this 
new lens was termed a portrait lens, and it required a very 
short exposure as compared with Daguerre’s previous 
achievements. 

Having witnessed the bending of light in the illustra¬ 
tions opposite page 254,1 do not think that any reader will 
have a difficulty in understanding how it is that a glass 
lens bends the rays. The bending occurs when the rays 
pass from a medium of one density (the air) into a 
medium of a different density (the glass), and again as the 
rays leave the glass and enter the air. The bending is 
therefore controlled by the curvature of the lens on both 
sides. 

I have repeatedly heard amateur photographers say that 
it is altogether a matter of chance whether one gets a 
good, bad, or indifferent lens when one purchases a camera. 
There is a certain amount of truth in this if one refers 
only to cheap cameras, and does not include expensive 
lenses. The reason for this is not far to seek. A great 
many defects may occur in the making of a lens, or flaws 
may be found in the glass only when the lens is polished 
and practically ready for use. The lens-maker has already 
expended a good deal of money on this faulty lens, and 
he can only afford to destroy it provided he is to get a 
compensative price for a good one when he does make it 
perfect. In the case of cheap lenses he must just do the 
318 


A CAMERA WITHOUT A LENS, &c. 

best he can; some are sure to be better than others. 
With expensive lenses, however, the case is different; he 
is willing to throw on one side all those wherein any fault 
occurs, no matter at what point in the process of manu¬ 
facture the defect is detected. 

Very great perfection has been arrived at in the making 
of lenses, but it must be clear that these results cannot 
have been attained in any haphazard fashion, nor could 
they have been very well arrived at by experiment. If 
lenses had been plastic bodies, which could be tried first of 
all in one shape and then squeezed out into another form, 
a purely experimental method might have been possible. 
Although I have stated at one point that a lens is elastic, 
it goes without saying that the elasticity is very slight 
and that the lens is in no degree plastic. We have seen 
that the making of a lens is no simple matter, even when 
the operator already has the necessary tools bearing the 
exact formation required for the particular lens which he 
desires to make. 

The curvatures of the lenses required have all been 
determined by mathematical calculation, and then a tool 
has been made in agreement with the form worked out by 
the mathematician. 


3i9 


CHAPTER XXII 


HOW LIGHT MAKES THE 
PHOTOGRAPH 

The chemical action of light—The latent image—A simple demonstra¬ 
tion—What is “ chemical change ” ?—A curious compound—Light 
decomposes some substances—What happened on Daguerre’s 
plates—A simple analogy—Modern photographic plates—Develop¬ 
ing and fixing—Photographic papers—Toning and fixing the 
prints—The rays of light which take part in photography—What 
are orthochromatic plates ?—Special purposes of other plates. 

T HE careful housewife, especially if she lives in the 
country, makes use of the direct chemical action of 
light, although she may not be aware of the fact. 
When she finds that the modern laundry has failed to 
make her cotton fabrics white enough, she simply passes 
the order on to the great bleacher Light. She places the 
cotton fabrics, in a wet condition, out of doors, and, as 
she says, “ bleaches them in the open air.'” She really 
gets Light to do what the chemical agencies of the 
laundry-man have failed to do to her satisfaction. 

This may not appear to be a very suitable analogy for 
the effect of light upon a photographic paper. The 
former is a bleaching-out process, while the latter is a 
colouring or darkening process. But if light can make 
some things white and other things black, then the 
difference must necessarily lie within the things which are 
being attacked by the light. It is obvious, therefore, 
320 


HOW LIGHT PHOTOGRAPHS 


that light is a force which sets up definite chemical 
actions, but that the particular effect produced will de¬ 
pend upon the nature of the substances themselves. 

What about the latent or invisible image upon a 
photographic plate ? In this case there is no visible 
change made by the light, but that there has been a real 
change effected may be demonstrated at the expense 
of a couple of photographic plates. Suppose that we 
have two similarly sensitised photographic plates, each 
enclosed in a dark envelope. We open one of the 
envelopes and take the plate out so that the daylight 
may fall upon it for a moment. We take care that the 
other plate is well protected from light. We then take 
the two envelopes into the dark room, and examine the 
plates by the light from a red or yellow lamp. Both 
plates look exactly alike; there is really no visible 
change. Each plate has a creamy white film over one 
side. We place the plates side by side in a developing 
tray filled with a certain chemical solution, and very soon 
we see that there is a marked difference between the two 
plates. One of the plates has become black all over, 
while the other remains unchanged. The change has 
taken place in the plate which was momentarily exposed 
to the action of light. 

If we now place the two developed plates in a fixing 
solution, we shall find the white film to clear off the 
plate unaffected by light, so that it becomes practically a 
clear sheet of glass, although there remains a transparent 
gelatine film. The black plate comes out of the fixing 
solution with practically the same appearance as it had 
when taken from the developing bath. 

321 


x 


HOW LIGHT MAKES 


Now it is quite apparent that the two plates have had 
exactly the same treatment throughout, with the one 
exception, that light was allowed to attack the one and 
not the other. We require no further evidence to con¬ 
vince us that light has a very real action. 

What, then, do we mean by chemical change ? The 
question hardly calls for an answer. Almost every one 
knows that in nature there are a certain number of 
simple or elementary substances, and that all the rest 
of nature is made up of combinations or compounds of 
two or more of these elements. But we must not think 
of a compound as a mere mixture. We may mix ground 
rice and sugar together; we have not made a compound. 
The rice and sugar are there just as before, and we might 
separate them again ; indeed, if we were to sprinkle some 
of the mixture into a glass of water, we should see the 
sugar fall quickly to the bottom of the glass, while 
the ground rice would float upon the surface for some 
time. 

If we think of any common chemical compound, we 
shall see at once how different it is from a mere mix¬ 
ture. We know that common table salt is a compound 
of sodium and chlorine. Now sodium is a soft metal, 
which one may cut with a knife, and which if cast upon a 
wet surface will catch fire. Fortunately for us, sodium 
behaves in a more orderly manner when it enters into 
partnership with chlorine. If it were otherwise we could 
not drop it into our soup and place it within our moist 
mouths, without its immediately igniting. The other 
partner in this combination, which is known as sodium 
chloride in the chemical “directory,” or as common salt 
322 


THE PHOTOGRAPH 


in the household, is the gas chlorine, which possesses a 
strong suffocating odour. 

We might take water as another example showing how 
completely the elements lose their individuality while 
they are in partnership. We know that water is entirely 
composed of two gases—hydrogen and oxygen; but when 
we drink water we do not drink a mixture of gases. We 
see then that chemical change means more than a mere 
addition. 

The chemical effect of light is not necessarily a com¬ 
bination or union of two or more substances. Light 
causes some combinations to disunite or decompose. 

If we wish to impress any one with the fact that light 
causes certain substances to unite, we have a well-known 
experiment at hand. If some chlorine and hydrogen 
gases are mixed together in a glass globe and then ex¬ 
posed to light, the gases will unite in a vigorous manner, 
announcing their union by a considerable explosion. For¬ 
tunately the chemical changes which occur on our 
photographic plates are not of such a sensational char¬ 
acter. 

It will be of interest to form some idea of the way in 
which light makes the photograph. Our best plan will 
be to consider in the first place what happened on 
Daguerre’s silvered plates. It will be remembered that 
the first step in Daguerre’s process was to get iodine to 
unite with the silver coating on the surface of his copper 
plate. This he accomplished in a very simple manner. 
He heated the iodine so that some ascended in the form 
of vapour, and in this form it came in contact with the 
silver of the plate. The two substances united chemic- 
323 


HOW LIGHT MAKES 


ally. For our present purpose we must be content to 
think of these two substances as having a natural attrac¬ 
tion or affinity for each other, thus causing them to join 
in partnership. 

It will be obvious that the partnership is not a very 
permanent one, for Daguerre had to take great care to 
keep his prepared plate away from the gentle action of 
light until such time as he had it arranged in position in 
his dark camera. The combination must be a very un¬ 
stable one when it can be so very easily upset or altered 
by the action of light falling upon it. This very insta¬ 
bility gave Daguerre his chance of success. 

Having got his plate safely within the dark camera, 
Daguerre opens the lens, whereupon a light-and-dark 
image falls upon the prepared or sensitised plate. We 
picture a chemical commotion wherever light attacks the 
plate, while the original partnership still holds good at 
such places as lie under the dark parts of the image. An 
examination of the plate in the dark room would not 
show any visible change, and so we remember that it was 
by means of an accident that Daguerre discovered that 
there had been a real chemical change upon his plate. I 
refer to the magic cupboard, in which the good fairy 
“mercury 1 ’ produced a beautiful picture upon a plate 
which had shown no sign of change whatever when taken 
from the camera. And thus it was that Daguerre dis¬ 
covered that by exposing the invisible image to the vapour 
of mercury a visible picture was formed. But what made 
the picture appear ? 

Suppose, by way of analogy, that we had an iron 
target in which was embedded the design of a crown 
3 2 4 


THE PHOTOGRAPH 


made of soft clay. Matters are so arranged that the 
clay and the iron look exactly alike, and the whole forms 
a smooth, self-coloured surface. If we commenced 
throwing handfuls of white stones at the target, we should 
very soon find that some of the stones were sticking to 
some parts of the target and not to others. We there¬ 
fore take good care to strike every part of the target, 
and when we have done so we shall find the design of a 
crown standing out distinctly upon the unaffected back¬ 
ground of the target. 

The foregoing is certainly a very crude analogy, but it 
may be of assistance in making clear what happens when 
the plate with the invisible image is exposed to the 
vapour of mercury. The plate has been prepared by the 
artist Light; there is an invisible design. We bombard 
the plate with small particles of mercury, and these 
unite with that part of the surface which has been 
specially prepared by light. Those particles of mercury 
which strike the parts of the plate with which light has 
not meddled are simply thrown off again. These are 
represented in the analogy by the stones striking the iron 
parts of the target. In this way Daguerre’s beautiful 
pictures were built up. 

It will be observed that the parts of Daguerre’s plate 
which were not affected by light still remained sensitive 
to light, the plate having been kept all this time in the 
dark. It was therefore necessary to wash the remaining 
portion of this sensitive film away. This Daguerre did 
by washing the plate in salt water. 

Turning to modern photographic plates, we find light 
preparing an invisible picture upon the unstable chemical 

325 


HOW LIGHT MAKES 


surface. Then follows the developing bath, and we 
imagine the chemicals in the developer to be attracted 
by the prepared design and rejected by the unaltered 
portions of the chemical film. Thus the visible image 
appears in the film, but we must remove the unaffected 
portions. This process is known as “ fixing,'” but would 
be more descriptively named if it were called a 44 clear¬ 
ing 11 process. The chemicals in this bath have no effect 
upon the developed image, they simply dissolve away the 
unaffected portions of the film, which if allowed to 
remain would darken on further exposure to light, and 
thus destroy the picture. 

Leaving the production of the image upon the glass 
negative, we turn to the photographic print on paper. 
We have become familiar with the fact that light pro¬ 
duces a visible image upon one kind of photographic 
paper, while it produces a latent image upon another kind 
of paper. The former is called a 44 printing-out-paper ” 
(P.O.P.), and the active part of the sensitive coating is 
composed of silver chloride. The action of light is to 
darken the silver chloride, and so the chemical change is 
visible at once. Exactly what the chemical change is has 
not been definitely determined, but the darkened sub¬ 
stance possesses less chlorine than it did before it was 
attacked by light. 

The colour produced by this darkening process is not 
very pleasing, but it may be altered by washing the print 
in a 44 toning ,1 bath containing a solution of chloride of 
gold or other metal. The print is still sensitive to light, 
and what really happens is that the toning solution 
deposits a very finely reduced powder of gold upon the 
326 


THE PHOTOGRAPH 


darkened portions of the print. This operation is carried 
out in daylight, because the sensitive coating is not so 
easily affected by light as that upon a sensitised photo¬ 
graphic plate. 

After the print has had a more pleasing colour pro¬ 
duced by the toning bath, it is necessary to remove all 
the unaffected portions of the still sensitive coat. This 
is done by another chemical bath, originally salt water, 
but now a solution of hyposulphite of soda is used. This 
process, although simply a clearing process, is known as 
“ fixing the print. 11 

Having already considered the development of the 
latent image on the photographic plate, we need not 
trouble further with the similar development of the in¬ 
visible image produced on bromide paper. In this case 
the developed image will be a positive, as it has been 
printed through a negative. 

As the present volume does not endeavour to give any 
suggestions for the practice of photography, it may seem 
unnecessary to remark that the negatives and the prints 
are always well washed between each chemical bath. It is 
necessary to stop one chemical action before setting up 
another, and one does not wish to carry chemicals from 
one bath into another bath. 

In some of the earlier chapters I have had occasion to 
refer to the fact that ordinary daylight contains red, 
orange, yellow, green, blue, indigo, violet, and a great 
quantity of invisible rays. This fact is well demonstrated 
by analysing a beam of light through a glass prism. We 
have no difficulty then in testing the different part that 
each kind of light plays in photography. We have 
327 


HOW LIGHT MAKES 


already seen that this spectrum, falling upon a sensitised 
surface, makes practically no change where the red and 
orange rays fall. The yellow rays are almost equally in¬ 
active, while the green rays have also very little action. 
Looking at the visible spectrum, we have only blue, indigo, 
and violet rays left, and it is these rays, more particularly 
the bluish violet, which attack the chemicals upon the 
ordinary photographic plate. It will be remembered, 
however, that an attack is also made by an invisible foe, 
for the sensitive surface is affected far beyond the violet 
end of the spectrum. Indeed, we have seen that it is 
possible to take a portrait by means of these invisible 
rays alone (see illustration facing p. 196). We are there¬ 
fore quite familiar with the fact that a large proportion 
of the light which makes our photographs is quite 
invisible, and, indeed, that the very rays (yellow) which 
give us most light, according to our estimate of luminosity, 
are practically of no use in photography with ordinary 
plates. 

Attempts have been made to produce a photographic 
plate which should be affected by all colours in similar 
proportions to the effects produced in vision. It is 
impossible to do this perfectly, but the great difference 
between the ordinary photographic effect and that of our 
vision may be very considerably reduced, so that any 
coloured object may now be photographed without 
such strange results as might otherwise be produced. By 
way of illustration, let us take some extreme case. It 
may be asking too much of the reader to imagine a lady 
dressed in a bright yellow dress with blue trimmings upon 
it, but suppose we have found the required subject in a 
328 



By permission oj the Thornton-Pickard Co., Ltd. 

An Interior (Canterbury Cathedral) 

This photograph required an exposure of one hour, and was taken with a Thornton-Pickard 
Ruby camera. The very high roof made it a difficult subject, but it was overcome by having a 
rising front on the camera. 










































































THE PHOTOGRAPH 


circus rider. Her photograph would represent her in a 
black dress with light trimmings. The photographic 
chemist, however, has prepared surfaces which are sensi¬ 
tive, in certain degrees, to red, orange, yellow, and green 
rays. Plates prepared in this way are called orthochro - 
matic . 

The purpose of these orthochromatic plates is to repro¬ 
duce in the photograph a true proportion of light and 
shade. A yellow object is to look lighter and not darker 
than a blue object, as is the case in ordinary photographic 
plates, and so on. 

Then again we have plates specially prepared to be 
sensitive to one colour in particular, and these are of great 
service in photographing through the colour screens for the 
three-colour process of printing. 

When considering invisible rays, in an earlier chapter, 
we found that photographic plates had even been made 
sensitive to the rays below the red end of the spectrum. 
These, however, are of scientific value alone. 

The chemistry of photography is a very complex 
subject; much mystery still remains, and a thorough 
understanding of the knowledge that has been attained 
requires one to be familiar with chemical symbols and 
equations. It has only been possible in this chapter to 
give a very general idea of the way in which light makes 
a photograph. 


329 


CHAPTER XXIII 


CONCLUSION 

A MONG all the wonderful things that were discovered 
during the fruitful nineteenth century ,photography 
must ever hold a very high position. We have all 
become so familiar with the art that we have almost 
ceased to marvel at its achievements. 

We have no photographs of the late Queen Victoria as 
a girl. Even when she ascended the British throne there 
were no photographers to record the coronation scene. 
At that very time Daguerre, in France, and Fox Talbot, 
in England, were busy trying to entrap the image of the 
camera obscura. Now there are tens of thousands of men 
making photography their daily business, while a census 
of all the amateur photographers throughout the civilised 
world would make a library of very bulky volumes. 

If one seriously considers the fact that a whole living 
scene may be registered by photography in one-thousandth 
part of a second, one cannot but be impressed with the 
marvellous achievement. 

Think what a small fraction of time a second is, and 
try to imagine one-hundredth part of that. Then look at 
the illustration facing page 268, and consider that the 
whole detail of that picture was recorded in one five- 
hundredth part of a second. It is, indeed, difficult to 
realise this fact. 


33o 


CONCLUSION 


Of all the wonders related in connection with photo¬ 
graphy, I think the phenomenon of the latent image 
remains the most extraordinary. We place a plate with a 
chemically prepared surface in a dark box, which has 
a small opening with a glass window formed by several 
pieces of curved glass. We have a dark blind over this 
window, but we withdraw the blind for the smallest frac¬ 
tion of a second. What has happened ? We take the 
plate and examine it in a dark room by the aid of a red 
lamp. We see the plate exactly as it was when we 
placed it in the camera. We wash the plate in a 
chemical solution and a real picture almost immediately 
appears. 

Suppose for a moment that some one individual had 
discovered all this on his own account, before Daguerre or 
Fox Talbot had ever dreamt their first philosophic dreams 
of recording the image of the camera obscura. Imagine 
this one ingenious individual calling together a dozen 
learned men of his time. He explains to them that he 
can get light to give him a perfect picture at a moment’s 
notice, and he proposes to demonstrate this fact. 

We picture the twelve philosophers watching the 
inventor place his prepared plate within the dark box. 
They examine the prepared plate in the dark room, and 
are all satisfied that it contains no hidden picture. The 
very darkness of this room, however, appeals to most of 
them as a rather suspicious feature. The red illumination 
is very subdued. Going out of doors, they watch the 
experimenter arranging his dark box on its stand. Light 
is to draw the view before them. The onlookers marvel 
at the audacity of the man, merely lifting off the dark 
33i 


CONCLUSION 


shutter for a single moment. Another examination in 
the dark room, and all declare that the experiment is 
a failure, there is not the least sign of any picture. 
When the inventor explains that the picture is really 
there although it is invisible, I can imagine the twelve 
good men joining in a hearty laugh. The chemical bath 
into which the inventor proposes to put the pictureless 
plate is next examined, but there seems no room for any 
trickery there. With what incredulity would the on¬ 
lookers watch the plate as the inventor made the chemical 
solution flow to and fro over it. At last the semblance 
of a picture does appear. Another chemical bath for 
the plate, and the inventor hands it to one of the amazed 
philosophers to take out into the daylight. Truly mar¬ 
vellous, but, alas, everything is reversed! Black objects 
appear white, white objects appear black, and the right 
and left hand sides of the picture are transposed. The 
inventor explains that this reversal, instead of being a dis¬ 
advantage, is exactly what he desires, for he proposes 
giving each philosopher a corrected copy of the picture. 

The inventor produces a large sheet of white paper which 
he has prepared. He asks any one of the onlookers to cut 
from this sheet twelve pieces of paper, each equal in size to 
the glass plate. There can be no trickery here, for if the 
paper did contain any hidden pictures they would run a 
certain risk of being cut through the centre. This time 
the inventor explains that he will save the gentlemen the 
trouble of leaving the dark room. Having placed the 
glass picture on the top of one of the pieces of prepared 
paper, he simply produces a bright flash of light. He 
then places this piece of apparently pictureless paper in a 
332 


CONCLUSION 


chemical bath, and very soon a picture appears. Another 
chemical bath and the picture is handed to the philo¬ 
sophers, who hasten to examine it by daylight. This 
picture is true to nature—black objects appear black, 
white appears white, the right and left hand sides are as 
they should be, and the whole variety of light and shade 
is perfectly portrayed. 

Of course, this demonstration never occurred just in 
the manner here described. I have merely asked the 
reader to draw upon his imagination in order to impress 
him with the true romance of photography. It has all 
happened, but not just so suddenly. Who can fail to be 
impressed with Daguerre’s accidental discovery of the 
latent image ? It reads far more like a fairy tale than 
real life. 

There must be few homes to-day in any civilised 
country in which photographs are not to be found. In 
many of our homes there are hundreds of such pictures. 

Passing over the sentimental side of the subject, it 
must be obvious to all that our knowledge has been very 
greatly extended by such photographs as travellers in 
distant lands have obtained and brought home. Every 
traveller is not an artist; but, armed with a camera and 
photographic plates, he can bring home faithful pictures 
of all the curious tribes and people he meets. We see the 
natives’ huts, their mode of living, and the strange vegeta¬ 
tion. In connection with exploration alone, photography 
has been of the very greatest interest and service. 

Instead of “ killing ” the painter’s art, photography has 
been of great assistance to the artist, in recording details 
which it would take too long to draw from nature. Then 
333 


CONCLUSION 

we benefit by the photographic reproductions of artistic 
masterpieces. 

We have seen how it is photography that provides us 
with the beautiful book illustrations of the present day. 

We have also seen how the eye of the camera has been 
able to look farther into the heavens than the human eye 
can do. Photography has faithfully recorded the presence 
of stars which man can never hope to see, even with the 
very best of telescopes. 

By means of photographs taken through the micro¬ 
scope, the student may examine the invisible germs of 
disease and learn to recognise the forms of different 
bacteria. 

The surgeon photographs the living skeleton and 
records the daily progress of a troublesome fracture. 
Indeed, photography enters into the whole realm of 
science, assisting in a multitude of different ways. 

Returning for a moment to the pictorial side of the 
subject, and passing over the marvellous living pictures 
which photography gives us through the medium of the 
cinematograph, it is interesting to note that permanent 
records of important subjects are being stored in the 
British Museum and elsewhere. The National Photo¬ 
graphic Record Association reports that about four thou¬ 
sand records have been lodged already in the British 
Museum alone. These should prove of great interest to 
future generations. 

As regards the future of photography, he would be a 
bold man who would prophesy. Colour photography has 
got on to new lines recently, and its future looks more 
hopeful. 


334 


CONCLUSION 

It has now been found possible to transmit photographs 
by means of electricity. Is it possible that some day we 
may yet be able to see the distant friend as he speaks to 
us by telephone ? 

It must be admitted by the least enthusiastic that 
during the last fifty years photography has done extra¬ 
ordinary things; and may we not hope that still more 
wonderful achievements will be accomplished by this great 
invention of the nineteenth century ? 


335 

























































APPENDIX 


T HE more studious reader may be glad to have the 
following synopsis of historical facts and dates, arranged 
in a convenient form for reference. 

DISCOVERY OF PHOTOGRAPHY 

1550 

The alchemists of the sixteenth century observed that 
silver ores changed colour when taken from the mine. 
They also made silver nitrate. 

1558 

Giovanni Battista della Porta exhibited a camera obscura 
to his friends in Italy; he was not the inventor. 

1727 

Johann Heinrich Schultze, a German physician, amused 
his friends by getting light to print stencil designs upon a 
liquid mixture of chalk and silver nitrate. He then caused 
the printing to disappear by shaking the bottle. It is 
obvious that he only looked upon the phenomenon as an 
amusing incident. 

1737 

Hellot coated paper with a solution of silver nitrate, and 
showed that it was darkened by exposure to light. His only 
concern, however, was to make a secret ink. The solution 
was colourless, and hence the writing was invisible until 
exposed to light. 

1774 

Charles William Scheele, a Swedish chemist, studied the 
chemistry of the action of light on silver salts. He found 
that the violet rays of the spectrum were by far the most 
active. 


Y 


337 


APPENDIX 


1791 

Thomas Wedgwood, a son of the great potter, made 
contact prints of opaque objects upon paper prepared with 
silver salts, but he could not fix them. 

1795 

Lord Brougham is stated to have suggested a way of 
making “ permanent ” the image of the camera obscura, by 
allowing it to fall upon a "surface of ivory rubbed with 
silver nitrate.” He sought to do this through the Royal 
Society, but he declared afterwards that the secretary 
deleted this suggestion from the paper. No doubt it was 

considered impracticable. 

1 1801 

J. W. Ritter, of Jena (Germany), discovered that paper 
prepared with silver chloride was darkened by the invisible 
rays beyond the violet end of the spectrum. 

1802 

Thomas Wedgwood and Sir Humphry Davy read a 
paper before the Royal Institution (London) on securing 
copies of drawings made on glass, by placing these in 
contact with paper or white leather prepared with silver 
nitrate. They failed to make the prints permanent. These 
experimenters tried to entrap the image of the camera 
obscura, but found the light insufficient for the chemicals 

upon their paper. 

F F 1 1810 

J. T. Seebeck was able to produce the colours of the 
spectrum upon moist chloride of silver. The results were 
very imperfect and could only be examined in a very subdued 
light, while they soon disappeared on exposure to the air. 

1813 

Joseph Nic^phore Niepce, of CMlons-sur-Saone, France, 
tried to prepare lithographic stones by the action of light. 
He made the drawing transparent and then tried to print it 
on to the surface of the stone, which he had previously 
treated with silver salts. He could not fix the results; the 
stone soon blackened all over its surface. 

338 


APPENDIX 


1816 

Niepce tried seriously to fix the image of the camera 
obscura. With very long exposures he obtained some 
imperfect results, but could not fix them. A few years later 
he was successful in making permanent prints of drawings 
on bitumen of Judea. He called his process “heliography.” 
His next attempt was to fix the image of the camera obscura 
by this means, and he succeeded in some measure, though 
the pictures must have been more like shadows or profiles. 

1824 

Louis Jacques Mand6 Daguerre, a scene painter in Paris, 
endeavoured to fix the image of the camera obscura, in order 
to help him in his profession. He first of all tried the silver 
salts, but with little success. 


1829 

Niepce and Daguerre revealed their secrets to one another 
and joined in partnership. 

1833 

Niepce died, having seen but little advance during his 
partnership. Daguerre soon abandoned the old process and 
got on to new lines. 

1835 

William Henry Fox Talbot, an English gentleman of 
means, who had been making experiments since 1833, 
succeeded in obtaining pictures of his country residence, by 
means of the camera obscura and paper prepared with silver 
salts. He had not heard of the experiments previously 
made by Wedgwood and Davy, nor was he aware that 
Daguerre was at work upon this subject in France. 

1838 

Daguerre accidentally discovered a means of developing 
the latent image. Along with Niepce junior, he received a 
pension from the French Government for disclosing the 
secret of the daguerreotype process. 

339 


APPENDIX 


1839 

Fox Talbot, disappointed at having been forestalled by 
Daguerre, made known his process of “photogenic drawing.’* 
Talbot’s invention was really the basis of modern photo¬ 
graphy. He produced a negative from which any number 
of positives could be printed. 

1839 

Some months later Daguerre’s process was publicly 

explained in Paris. 

F 1839 

Sir John Herschel proposed hyposulphite of soda for 
"fixing” the pictures instead of common salt, as formerly used. 

1840 

J. Goddard, a lecturer in London, applied bromine to 
Daguerre’s plates, along with the iodine, and made a much 
more sensitive surface, thus greatly reducing the time 
required for exposure. 1Q4Q 

Photographic studios were opened in Great Britain. 

1841 

Special photographic lenses were made for the first time. 
These reduced the time of exposure to one-tenth of that 
previously required. 1841 

Fox Talbot patented his later process of "calotype,” in 
which the sensitiveness of his paper negatives was greatly 
increased. He used iodide of silver and a solution of gallic 
acid and silver nitrate. 

1841 

Up to this time the processes of developing, etc., were 
carried on in total darkness. At this date a patent was 
taken out for the use of red lamps. 

1848 

Niepce de St. Victor, a nephew of the original Niepce, 
introduced the process of coating glass plates with albumen 
containing iodide of potassium, and then sensitising them by 
dipping them in a bath of silver nitrate before exposing them. 

340 


APPENDIX 


1851 

Frederick Scott Archer, a London sculptor, introduced 
the wet collodion process. 


1855 

Dr. Taupenot, in France, produced the first dry plates. 

1864 

Sayce and Bolton used collodion emulsion for making dry 
plates. 

1871 

R. L. Maddox substituted gelatine for the collodion 
emulsion, but these plates did not come into use till some 
years later. 


BOOK ILLUSTRATIONS 

1826 

Niepce copied drawings in line on to metal plates by 
means of light. He prepared the plates with a surface of 
bitumen of Judea, and etched the exposed lines with acid. 
He used the etched plates for printing. 

1839 

Mungo Ponton demonstrated the fact that potassium 
bichromate, when dried, was changed by exposure to light, 
and that the unexposed parts might be washed away. This 
gave us the basis of the modern processes of transferring 
photographs to the surface of printing blocks. A few years 
later Fox Talbot practised what we now call photogravure. 

1876 

Zincotype, or line drawings reproduced on zinc blocks, 
by photography. 

Half-tone process, by which any photograph may be 
reproduced on printing blocks. 

1896 

The three-colour process of printing. 

34i 


APPENDIX 


MISCELLANEOUS 

1892 

Animated pictures. Edison’s kinetoscope, followed in 
1895 by Lumiere’s cinematograph. 

1895 

Colour photography. Ives, of Philadelphia, took three 
separate photographic records, through red, green, and violet 
colour screens. He then reproduced the colour picture by 
means of three magic lanterns, using the same colour screens. 
All the other processes of colour photography were subse¬ 
quent to this. 

4 1895 

X-ray photography. 

1907 

Professor Korn perfected his system of telegraphing 
photographs over great distances. 


It may be of interest to note how the time of exposure 
required for taking photographs was gradually decreased by 
each successive invention. 


Niepce’s heliography in 1827 required an exposure of 6 hours. 
Daguerre’s process in 1839 ,, 

(afterwards greatly reduced) 

Talbot’s calotype in 1841 „ 

Archer’s wet collodion in 1851 „ 

Dry plates (gelatine) in 1878 ,, 

Fast plates to-day „ 


» 10 0 0 


30 minutes 

3 minutes 
10 seconds 
1 second 
th second 


Electric spark photographs taken in about 


r th second 


It may also be of interest to note the different periods 
during which the different processes held sway. 

Daguerreotype was practised from 1839 to 1854. 
Talbotype „ „ 1841 to 1855. 

Wet collodion „ „ 1851 to 1880. 

After this the arrival of the dry plate very quickly made 
photography a popular pastime. 


THE END 








INDEX 


Abney, Sir William, 290 
Absorption, colour, 78 
Alchemists, 19, 20 
Arago, 39 

Archer, Frederick Scott, 57, 59, 
122 

Bacteria, 217 
Battista Porta, see Porta 
Becquerel rays, 202, 204 
Bitumen of Judea, 30, 119 
Book illustrations, 116 
Bromide paper, 263, 327 
Bromine, 63 
Bullets, flying, 292 

Camera, the largest, 264 
Camera obscura, 15, 17, 30^ 45 
Calotype, 52, 342 
Carbon tissue, 137 
Carte-de-visite, 64 
Chemical change, 322 
Chevalier, 27 
Cholera microbe, 218 
Cinematograph, 67 
Coal mine, 223 

Collodion process (wet), 57, 122, 
342 

Collotype, 138 
Colour addition, 147 


Colour, nature of, 74, 76, 145 
Colour photography, 72 
Colour pigments, 88, 145 
Colours, primary, 76, 150 
Colour subtraction, 101, 147, 152 
Criminals and photography, 157 

Daguerre, 25, 72, 113, 317, 323, 
339 

Daguerreotype, 24, 38, 52, 55, 
62, 275, 323, 342 
Davy, Sir Humphry, 21, 45 
Developing, 326 
Diphtheria microbe, 218 
Dry plates, 58, 342 

Earthquake records, 303 
Edison, 67 

Electric-spark photography, 65, 
293 * 342 , 

Engraving, 117 
Enlarging photographs, 262 
Etching, 118, 127, 137 
Ether vibrations, 76 
Eye, the, 244 

Faking photographs, 274 
Faraday, Michael, 50 
Finger-prints, 161, 169 
Fish-eye photograph, 301 


343 



INDEX 


Fixing, 326 
Forgeries, 175 

Goddard, John Frederick, 63 

Half-tone printing process, 128, 
341 

Heliography, 31, 32, 120, 342 
Herschel, Sir John, 37, 52 
Hyposulphite of soda, 37 

Instantaneous photography, 54, 
63, 64 

Intaglio printing process, 118,135 

Inverted image, 249 

Invisible rays, 176 

Iodine, 33, 50, 63, 323 

Ives’ colour photography, 86 

Joly’s colour photography, 94 

Keartons, 266 
Kinetoscope, 67 
Korn, Professor, 236 

Latent image, 35, 51, 125, 321, 
3 2 5 > 332 
Lens, 16, 313 

Lensless photography, 310 
Light, white, 77 
Lightning, dark, 307 
Lippmann’s colour photography, 
109 

Lockjaw microbe, 218 
Lumiere, 67, 99 


Microbes, 209 
Microscope, 209 

Nature’s camera, 244 
Nature photography, 266 
Negative, 51, 55, 59, 97 
Niepce, Joseph Nicephore, 27, 
119, i35» 338 
Niepce, Isidor, 32 

Patent, Daguerre’s, 41, 42 
Pencil of Nature , 46, 52, 176 
Pension, Daguerre’s, 39, 40 
Photogenic drawing, 51 
Photograph, the largest, 260 
Photogravure, 137 
Photo-micrography, 209 
Picture post cards, 139 
Pinhole photography, 310 
Porta, Battista, 15, 26 
Primary colours, 76, 150 
Prism, glass, 75, 77 
Process screen, 131, 155 

Radium, 204 

Refraction of light, 215, 253 
Relief printing processes, 118 
Rontgen rays, 179 

Salt, 22, 48, 49 

Sanger-Shepherd’s colour photo¬ 
graphy, 99 
Scheele, 337 
Schillings, 268 
Schultze, 337 
Scotland Yard, 159, 167 
Screens, colour, 81 


Mercury, 36, 324 


344 




INDEX 


Screens, process, 131, 155 
Selenium, 236 
Silver salts, 19, 21, 47 
Soap-bubbles, 74, 296 
Solarisation, 61 

Sound waves photographed, 292 
Spectroscope, 284 
Spectrum, 75, 177, 285, 328 
Spotted-fever microbe, 219 
Subtraction of colour, 101, 152 
Star photography, 275 
Stereoscope, 258 
Stereophotochromoscope, 86 

Talbot, Henry Fox, 44, 64, 72, 
H3» 176, 339 


Talbotype, 52, 342 
Telegraphing photographs, 234 
Tele-photography, 265 
Three-colour process, 142, 341 
Tin photographs, 59 
Toning, 326 

Ultra-violet light, 197 

Wedgwood, 21, 45, 338 

Woodbury type, 135 

Wood’s colour photography, 112 

X-ray photography, 179 

Zincotype, 125, 341 


WILLIAM BRENDON AND SON, WD. 
PRINTERS, PLYMOUTH 








J. 






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day, February 9 th, at an Evening Meeting of the Royal Institution 
of Great Britain. 8vo. 6s. 

ON THE ARCHETYPE AND HOMOLOGIES OF THE VER¬ 
TEBRATE SKELETON. Twenty-eight Woodcuts, Two Folio 
Plates, and Three Tables of Synonymes. 8vo. 10 s. 

DESCRIPTION OF THE SKELETON OF AN EXTINCT 
GIGANTIC SLOTH. With Observations on the Osteology, na¬ 
tural Affinities, and probable Habits of the Megatherioid Quadrupeds 
in general. 4 to. 11 . 12 s. 6 d. 

DESCRIPTIVE AND ILLUSTRATIVE CATALOGUE OF THE 
PHYSIOLOGICAL SERIES OF COMPARATIVE ANA¬ 
TOMY, contained in the Museum of the Royal College of Surgeons 
in London. 5 vols. 4 to., each 11 . 11 s. 6 d. 

CALCULI AND OTHER ANIMAL CONCRETIONS, 10 s. plain, 
1 Z. 11s. 6 d. coloured. 

FOSSIL ORGANIC REMAINS OF MAMMALIA AND 
BIRDS. 21 s. 

By if. a. $aleg, M.A. 

A MANUAL OF GOTHIC MOLDINGS. A Practical Treatise 
on their Formation, Gradual Development, Combinations, and Varie¬ 
ties; with full Directions for copying them, and for determining their 
Dates. Second Ed., Illustrated by nearly 600 Examples. 8vo. 7 s. 6 d. 


JOHN VAN VOORST, 1 , PATERNOSTER ROW. 




6 


WORKS PUBLISHED BY MR. VAN VOORST. 


By fHr. ( continued ). 

THE CHURCH RESTORERS; A Tale, Treating of Ancient and 
Modern Architecture and Church Decorations. Foolscap 8vo. 4 s. 6 d. 

A MANUAL OF GOTHIC ARCHITECTURE. With a full 
Account of Monumental Brasses and Ecclesiastical Costume. Fools¬ 
cap 8 vo. with 70 Illustrations, 6s. 6 d. 

By £Tf)0 llcb. £ 1 . (Sx. $ 3 urff) 3 S, Precentor of St. John's College , Bishop's 
Auckland , New Zealand. 

FIRST LESSONS FOR SINGING CLASSES. Post 8vo. 2 s. 6 d. 

By ^ritreaux John F.L.S., M. W.S., fc. 

A HISTORY OF BRITISH FOREST-TREES, Indigenous and 
Introduced. Nearly 200 Engravings. 8vo. 28 s., royal 8vo. 21 . 16 s. 

By <£&muntr ^fjarpe. M.A., Architect. 

A TREATISE ON THE RISE AND PROGRESS OF DECO¬ 
RATED WINDOW TRACERY IN ENGLAND. Illustrated 
with 97 Woodcuts and 6 Engravings on Steel. 8vo. 10 s. 6oL—And 

A SERIES OF ILLUSTRATIONS OF THE WINDOW 
TRACERY OF THE DECORATED STYLE OF .ECCLESI¬ 
ASTICAL ARCHITECTURE. 60 Steel Engravings, with De¬ 
scriptions. 8 vo. 21s. 

ARCHITECTURAL PARALLELS; or, The Progress of Ecclesias¬ 
tical Architecture in England, through the Twelfth and Thirteenth 
Centuries, exhibited in a Series of Parallel Examples selected from 
Abbey Churches. 121 Plates in tinted outline, each 18 in. by 12 
in. half morocco. 13 £. 13 s., or large paper, 16 £. 10 s. 

By 13. Wartr, F.L.S. 

ON THE GROWTH OF PLANTS IN CLOSELY-GLAZED 
CASES. 8vo. 5 s. 

By James p>etoctson Wilson, F.L.S., $c. 

A TRANSLATION OF DE JUSSIEU’S ELEMENTS OF BO¬ 
TANY. 12 mo„ with 750 Woodcuts, 12 s. 6 d. 

By J. E. Wilson. 

A BRIEF HISTORY OF CHRIST’S HOSPITAL, from its 
Foundation by King Edward the Sixth. Seventh Edition, with Six 
Illustrations, and a List of the Governors. 12 mo. 4 s. 

By Charles Wootitoartr, F.R.S. 

A FAMILIAR INTRODUCTION TO THE STUDY OF PO¬ 
LARIZED LIGHT ; with a Description of, and Instructions for 
Using, the Table and Hydro-Oxygen, Polariscope and Microscope. 
8 vo., Illustrated, 3 s. 

By William ¥arrell. F.L.S., v.P.z.s ., $c. 

A HISTORY OF BRITISH BIRDS. This work contains a his¬ 
tory and a portrait of each species of the Birds found in Britain. 
The three volumes contain 535 Illustrations. Second Edition. 
3 vols. demy 8vo. 4 d. 14 s. 6 d. Royal 8vo. 91 .; or imperial 8vo. 1 31 . 10 s. 
A Supplement to the first edition, demy 8vo. 2 s. 6 d.; royal 8vo. 5 s.; 
imperial 8vo. 7 s. 6 d. 


JOHN VAN VOORST, 1 , PATERNOSTER ROW. 




WORKS PUBLISHED BY MR. VAN VOORST. 


r 


By j!Hr. kartell ( continued ). 

A HISTORY OF BRITISH FISHES. Second Edition, in two 
vols. demy 8vo., Illustrated by nearly 500 Engravings, 3 /. A Sup¬ 
plement to the First Edition, demy 8vo. 7 s. 6 d royal 8vo. 15 s.; 
imperial 8vo. \l. 2s. 6 d. 

A PAPER ON THE GROWTH OF THE SALMON IN FRESH 
WATER. With Six Illustrations of the Fish of the Natural Size, 
exhibiting its structure and exact appearance at various stages during 
the first two years. 12s. sewed. 


BAPTISMAL FONTS. A Series of 125 Engravings, Examples of the 
different Periods, accompanied with Descriptions; and with an In¬ 
troductory Essay by Mr. Paley. 8vo. lL Is. 

A CATALOGUE OF BRITISH VERTEBRATED ANIMALS, 
derived from Bell’s Br. Quadrupeds and Reptiles, and Y arrell’s Br. 
Birds and Fishes; so printed as to be applicable for labels. 8vo. 2 s. 6 d. 

A CABINET EDITION OF THE HOLY BIBLE; the Authorized 
Version. With 24 highly-finished steel Engravings. The Historical 
subjects from the most esteemed paintings of the Old Masters, and 
the Landscapes from drawings by W. Westall, A.R.A. In em¬ 
bossed binding, 10s. 6c?. 

A CABINET EDITION OF THE BOOK OF COMMON PRAYER; 
the Authorized Version. With 10 Engravings, executed in the best 
manner, on steel. In embossed binding, 4 s., uniform with the 
Cabinet Bible. 

DOMESTIC SCENES IN GREENLAND AND ICELAND. 16 mo., 
Illustrated, 2 s. 6 d . 

ELEMENTS OF PRACTICAL KNOWLEDGE; or, The Young 
Inquirer answered. Explaining, in question and answer, and in 
familiar language, what most things daily used, seen, or talked of, 
are ; what they are made of, where found, and to what uses applied. 
Second Edition, 18 mo., with Illustrations, 3 s. 

EVENING THOUGHTS. By a Physician. Post 8vo. 4 s. 6 d. 

THE FIRST PRINCIPLES OF RELIGION, and the Existence of a 
Deity, explained in a Series of Dialogues adapted to the capacity of 
the Infant mind. 18 mo. 2 s. 

INSTRUMENTA ECCLESIASTICA : a Series of 72 designs for the 
Furniture, Fittings, and Decorations of Churches and their Precincts. 
Edited by the Ecclesiological, late Cambridge Camden, Society. 4 to. 
11 . 11 s. 6 d .—A second series is now in course of publication. 

LETTERS FROM THE VIRGIN ISLANDS, illustrating Life and 
Manners in the West Indies. Post 8vo. 9 s. 6 d. 

THE LETTERS OF RUSTICUS OF GODALMING. 8vo., with 
Illustrations, 8s. 6 d. 

LITTLE FABLES FOR LITTLE FOLKS. Selected for their 
moral tendency, and re-written in familiar words, not one of which 
exceeds two syllables. 18 mo. Is. 6 d. 

THE POOR ARTIST ; or, Seven Eye-Sights and One Object. Fcap. 
8 vo. 5 s. 


JOHN VAN VOORST, 1 , PATERNOSTER ROW. 





8 


WORKS PUBLISHED BY MR. VAN VOORST. 


Illustrated Meprints. 

AIKIN’S CALENDAR OF NATURE ; or, Natural History of each 
Month of the Year. With additions, by a Fellow of the Linnaean 
and Zoological Societies, and 18 designs by Cattermole. Small 8vo. 
2 s. 6 d. In ordering this volume “ Cattermole’s Edition ” should be 
particularly expressed. 

BLOOMFIELD’S FARMER’S BOY, and other Rural TALES and 
POEMS. With 13 Illustrations by Sidney Cooper, R.A., 
Horsley, Frederick Tayler, and Thomas Webster, R.A. 
Foolscap 8vo. 7 s. 6 d ., large paper, 15 s. 

DODSLEY’S ECONOMY OF HUMAN LIFE. In 12 Books, with 
12 Plates, engraved on steel, from original designs, by Frank 
Howard, Harvey, Williams, &c. 18 mo., gilt edges, 5 s. 

GOLDSMITH’S VICAR OF WAKEFIELD. With 32 Illustrations 
by William Mulready, R.A.; engraved by John Thompson. 
\l. Is. square 8vo., or 36 s. in morocco. 

GRAY’S ELEGY IN A COUNTRY CHURCH-YARD. Each 
Stanza illustrated with an Engraving on Wood, from 33 original 
Drawings expressly made for the volume, by the most eminent 
Artists. Post 8vo. 9 s.—A Polyglot Edition of this volume, with 
inter-paged Translations in the Greek, Latin, German, Italian, and 
French languages. 12 s. 

GRAY’S BARD. With Illustrations from Drawings by the Hon. 
Mrs. John Talbot. Uniform with the Elegy of Gray, to which it 
forms an appropriate companion volume. 7 s. 

SHAKSPEARE’S SEVEN AG 3 S OF MAN. Illustrated by Wm. 
Mulready, R.A. ; J. Constable, R.A.; Sir David Wilkie, 
R.A.; W. Collins, R.A.; A. E. Chalon, R.A. ; A. Cooper, 
R.A.; Sir A. W. C lcott, R.A. ; Edwin Landseer, R.A.; 
W. Hilton, R.A. .—A few copies of the First Edition in 4 to. 

remain for sale. 

WATTS’ DIVINE AND MORAL SONGS. With 30 Illustrations 
by C. W. Cope, R.A.; engraved by John Thompson. Square 
8vo. 7 s. 6 d ., or 21s. in morocco. 

WHITE’S NATURAL HISTORY OF SELBORNE. A New Edi¬ 
tion, with Notes by the Rev. Leonard Jenyns, MA., F.L.S., &c. 
With 26 Illustrations. Foolscap 8vo. 7 s. 6 d. 

Shortly will be Published. 

GOODSIR’S (R. A.) ARCTIC VOYAGE. 

ANSTED’S (PROFESSOR) ELEMENTARY COURSE OF GEO¬ 
LOGY, MINERALOGY, AND PHYSICAL GEOGRAPHY. 

JOHNSTON’S (DR.) INTRODUCTION TO CONCHOLOGY. 

LATHAM’S (DR. R. G.) NATURAL HISTORY OF MAN. 

KNOX’S (A. E.) GAME BIRDS AND WILD FOWL. 

The Illustrations to the Works enumerated in this Catalogue have been de¬ 
signed or drawn and engraved expressly for the W(yrks they respectively 
embellish , and they are never used for other Works. 



JOHN VAN VOORST, 1 , PATERNOSTER ROW. 











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